OA21100A

OA21100A - Magnetic assemblies and methods for producing optical effect layers comprising oriented platelet-shaped magnetic or magnetizable pigment particles.

Info

Publication number: OA21100A
Application number: OA1202200493
Authority: OA
Inventors: Evgeny LOGINOV; Christophe BAUDRAZ; Claude Alain Despland
Original assignee: Sicpa Holding Sa
Filing date: 2021-05-21
Publication date: 2023-11-13

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 magnetic assemblies and methods for producing optical effect layers (OELs) on a substrate, said method comprising a step of exposing a coating composition comprising platelet-shaped magnetic or magnetizable pigments particles.

Description

MAGNETIC ASSEMBLIES AND METHODS FOR PRODUCING OPTICAL EFFECT LAYERS COMPRISING ORIENTED PLATELET-SHAPED MAGNETIC OR MAGNETIZABLE PIGMENT PARTICLES

FIELD OF THE INVENTION

The présent invention relates to the field of magnetic assemblies and methods for producing optical effect layers (OELs) comprising magnetically oriented platelet-shaped magnetic or magnetizable pigment particles. In particular, the présent invention provides magnetic assemblies and methods for magnetically orienting platelet-shaped magnetic or magnetizable pigment particles in coating layers so as to produce OELs and the use of said OELs as anticounterfeit means on security documents or security articles as well as décorative purposes.

BACKGROUND OF THE INVENTION

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 éléments, 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, hâve been disclosed in WO 2002/090002 A2 and WO 2005/002866 Al.

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 dîfficult to detect, typically requiring specialized equipment and knowledge for détection, whereas “overf ’ security features rely on the concept of being easily détectable with the unaided human senses, e.g. such features may be visible and/or détectable via the tactile sense while still being dîfficult to produce and/or to copy. However, the effectiveness of overt security features dépends to a great extent on their easy récognition as a security feature.

Magnetic or magnetizable pigment particles in printing inks or coatings ailow 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 resuit is a fixed and stable magnetically induced image, design or pattern. Materials and technologies for the orientation of magnetic or magnetizable pigment particles in coating compositions hâve 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 Bl; US 2002/0160194; US 2004/0009308; EP 0 710 508 Al; WO 2002/09002 A2; WO 2003/000801 A2; WO 2005/002866 Al; WO 2006/061301 AU In such a way, magnetically induced patterns which are highly résistant 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.

The methods and devices described hereabove use magnetic assemblies to mono-axially orient platelet-shaped magnetic pigment particles. Mono-axial orientation of magnetic pigment particles resuit in neighboring particles having their main 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.

Wîth the aim of producing coatings or layers comprising bi-axially oriented magnetic or magnetizable pigment particles, methods for generating time-dependent, direction-variable magnetic fields hâve been developed, thus allowing the bi-axial orientation of magnetic or magnetizable pigment particles.

WO 2015/086257 A1 discloses a method for producing an optical effect layer (OEL) on a substrate, said process comprising two magnetic orientation steps, said steps consisting of i) exposîng a coating composition comprising platelet-shaped magnetic or magnétisable 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 magnétisable pigment particles and ii) exposîng the coating composition to a static magnetic field of a second magnetic-field-generating device, thereby mono-axially re-orientîng at least a part ofthe plateletshaped magnetic or magnétisable pigment particles according to a design transferred by said second magnetic-field-generating device.

EP 2 157 141 Al discloses magnetic-field-generating devices comprising a linear arrangement of at least three magnets that are positioned in a staggered fashion or in zigzag formation, each of said tliree magnets having its magnetic axis substantially perpendicular to the substrate surface and said at least three magnets at the same side of a feedpath hâve 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 în a coating composition move past the magnets (direction of movement depicted as an arrow). However, as known by the man skilled in the art, magnetic fields rapidly decrease with the distance between the magnets and the sample and therefore the feedpath ofthe magnetic-fîeld-generating devices in EP 2 157 141 AI are limited in width thus limiting the production of optical effect layers of large sizes. Furthermore, the process described in EP 2 157 141 Al would require long feedpaths with the conséquence of having a high number of magnets disposed in a staggered fashion, wherein said long feedpaths that are not compatible with the limited available space in industrial presses.

WO 2015/086257 Al, WO 2018/ 019594 Al and EP 3 224 055 B1 disclose devices and processes for producing optical effect layers (OEL) comprising magnetically bi-axially oriented platelet-shaped magnetic or magnetizabie pigment particles. The process discloses a step of exposîng the pigment particles to a dynamic magnetic field of a magnetic assembly comprising a Halbach cylinder assembly, wherein said Halbach assembly is, respectively, a linear Halbach arrays disposed on one side of the substrate carrying the orientable pigment particles in WO 2015/086257 Al and WO 2018/019594 Al and an Halbach cylinder assembly in EP 3 224 055 Bl. WO 2015/086257 Al and WO 2018/019594 Al may suffer from the same drawbacks as those described for EP 2 157 141 AI and EP 3 224 055 Bl requires the curîng of the layer to be carried out within the cylinder assembly thus rendering impossible a potential re-orientation step of the magnetic or magnetizabie pigment particles.

US 2007/0172261 Al discloses spinning magnets or magnetic assemblies generating radialiy symmetrical time-variable magnetic fields, wherein said magnets or magnetic assemblies are driven by a shaft (or spindle) connected to an extemal motor. CN 102529326 B discloses examples of devices comprising spinning magnets that might be suitable for bi-axially orienting platelet-shaped magnetic or magnetizabie pigment particles. WO 2015/082344 Al, WO 2016/026896 Al and WO 2018/141547 Al disclose shaft-free spinning magnets or magnetic assemblies constrained in a housing made of non-magnetic and are driven by one or more magnet-wire coils wound around the housing. However, spinning magnets or magnetic assemblies may suffer from difficulties in their use or împossibility of their use on industrial printing presses such as those as disclosed e.g. in EP 1 648 702 Bl or EP 1 961 559 Al.

Difficulties may include the need for important redesigns of existing industrial printing presses, including providing electric power and control signais to mn the motors of the spinning magnets. Therefore, a need remains for improved magnetic assemblies and methods for producing homogenous bi-axial magnetic orientation of platelet-shaped magnetic or magnétisable pigment particles comprised in coating layers to as to form optical effect layers (OELs), said methods being mechanically robust, easy to implement with an industrial high-speed printing equipment, in particular rotating magnetic cylinders, without resoiting to cumbersome, tedious and expensive modifications of said equipment. In particular, there is a need of compact magnetic assemblies with a wide feedpath/useable working area and methods also suitable for orienting magnetic or magnetizable pigments particîes over large printed areas as well as printed areas placed at a distance of up to 20 mm from said magnetic assemblies.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to overcome the défi ci en ci es of the prior art. This is achieved by the provision of a] magnetic assembly (xOO) for producing an optical effect layer (OEL) on a substrate (x20), said magnetic assembly (xOO) being configured for receiving the substrate (x20) in an orientation substantially parallel to a first plane and above the first plane, said the first plane being located above the upmost surface of the two second bar dipole magnets (x32_aand x32b) and further comprising:

a) at least a first set (SI) and a second set (S2), each of the first and second sets (SI, S2) comprising:

one first bar dipole magnet (x31 ) having a first thickness (Ll), a first length (L4) and a first width (L5), and having îts magnetic axis oriented to be substantially parallel to the first plane, two second bar dipole magnets (x32_a and x32b) having a second thickness (L2), a second length (L6) and a second width (L7), the two second bar dipole magnets (x32_a, x32b) having their upmost surfaces flush with each other, and having their magnetic axes oriented to be substantially perpendicular to the first plane, the first bar dipole magnet (x31) of the first set (SI) having a magnetic direction opposite to the magnetic direction of the first bar dipole magnet (x31) of the second set (S2), the first bar dipole magnets (x31 ) of the first and second sets (SI, S2) being spaced apart by a first distance (dl), the first bar dipole magnet (x31 ) of the first set (S 1 ) having substantially the same first length (L4) and first width (L5) as the first bar dipole magnet (x31) of the second set (S2), and the two second bar dipole magnets (x32_a and x32b) of the first set (SI) having substantially the same second lengths (L6) and second widths (L7) as the two second bar dipole magnets (x32_aand x32b) of the second set (S2), the first bar dipole magnet (x31) and the second bar dipole magnets (x32_a and x32b) of each of the first and second sets (S 1, S2) being aligned to form a column, in that the first bar dipole magnet (x31 ) of the first and second sets (S 1, S2) is respectiveîy placed between and spaced apart from the second bar dipole magnets (x32_a and x32b) by a second distance (d2).

the first width (L5) and the second length (L6) being substantially the same, the North pôle of one second bar dipole magnet (x32_a and x32b) of each of the first and second sets (SI, S2) pointing towards the first plane as the North Pôle of the first bar dipole magnet (x31) pointing towards said one, and the South pôle of the other of the second bar dipole magnet (x32_a and x32b) of each ofthe first and second sets (SI, S2) pointing towards the first plane and the South Pôle of the first bar dipole magnet (x31 ) pointing towards said other, and further comprising:

b) a first pair (Pl) of third bar dipole magnets (x33_a and x33b) having a third thickness (L3), a third length (L8) and a third width (L9) and having their magnetic axes orîented to be substantially parallel to the first plane, the second width (L7) of the two second bar dipole magnets (x32_a and x32b) of the first and second sets (SI, S2) having substantially the same value as the third width (L9) of the third bar dipole magnets (x33_a and x33b), each of the third bar dipole magnets (x33_a and x33b) being aligned with one second bar dipole magnet (x32_a and x32b) of the first set (SI) and one second bar dipole magnet (x32_a and x32b) of the second set (S2) so as to form two lines, the third bar dipole magnets (x33_a and x33b) being placed between and spaced apart from the respective second bar dipole magnets (x32_a and x32b) by a third distance (d3), the North pôles of the third bar dipole magnets (x33a and x33b) respectively pointing towards one of the second bar dipole magnets (x32_a and x32b) and the North Pôles of said ones of the second bar dipole magnets (x32_a and x32b) pointing towards the first plane or the South pôles of the third bar dipole magnets (x33_a and x33b) respectively pointing towards one of the second bar dipole magnets (x32_a and x32b) and the South Pôles of said ones of the second bar dipole magnets (x32_a and x32b) pointing towards the first plane, wherein the first bar dipole magnets (x31) ofthe first and second sets (SI, S2), the second bar dipole magnets (x32_a and x32b) of the first and second sets (SI, S2), and the third bar dipole magnets (x33_a and x33b) are at least partially embedded in a non-magnetic supporting matrix. Also described herein are uses of the magnetic assembly (xOO) described herein for producing the optical effect layer (OEL) on the substrate (x20) described herein.

Also described herein are printing apparatuses comprising the magnetic assembly (xOO) described herein being mounted in the vîcînity of a transferring device preferably selected from the group consisting of chaîns, belts, cylînders and combinations thereof.

Also described herein are methods for producing the optical effect layer (OEL) described herein on the substrate (x20) described herein and optical effect layers (OELs) obtaîned thereof, said methods comprising the steps of:

i) applying on a substrate (x20) surface a radiation curable coating composition comprising platelet-shaped magnetic or magnétisable pigment particles, wherein an X-axis and a Y-axis define a plane of prédominant extension of the particles, said radiation curable coating composition being in a first, liquid State so as to form a coating layer (xlO);

ii) exposing the coating layer (xlO) to a magnetic field of the magnetic assembly (xOO) described herein so as to bi-axialîy orient at least a part of the platelet-shaped magnetic or magnétisable pigment particles;

iii) at least partially curing the radiation curable coating composition of step ii) to a second, solid State so as to fix the platelet-shaped magnetic or magnétisable pigment particles in their adopted positions and orientations.

Also described herein optical effect layers (OELs) obtained by the methods described herein and/or by using the printing apparatuses described herein as well as their uses as anti-counterfeit means on documents and articles (in other words for protecting and authenticating documents and articles) as well as for décorative purposes.

The magnetic assemblies and methods provided by the present invention are mechanically robust, easy to implement with an industrial high-speed printing equipment, without resorting to cumbersome, tedious and expensive modifications of said equipment. Furthermore, the magnetic assemblies and methods of the present invention allows to bi-axially orient platelet-shaped magnetic or magnétisable pigment particles in a homogeneous manner and also suitable to produce optical effect layers over large printed areas as well as printed areas placed at a distance of up to 20 inm ffom said magnetic assemblies.

BRIEF DESCRIPTION OF DRAWINGS

The magnetic assemblîes (xOO) and the methods described herein for producing optical effect layers (OEL) on the substrate (x20) described herein are now described in more details with reference to the drawings and to particular embodiments, wherein

Fig. 1 schematically illustrâtes a platelet-shaped pigment particle.

Fig. 2A schematically illustrâtes a method for producing an optical effect layer (OEL) on a substrate (220) according to the present invention, wherein a coating layer (not shown in Fig. 2A) comprising platelet-shaped pigment particles moves (see the arrow) in the vicinity and on top of the magnetic assembly (200) so as to be exposed to the magnetic field of said magnetic assembly (200) and then at least partially cured with a curing unit (250). The magnetic assembly (200) comprises a first set (SI) comprising a first bar dipole magnets (231) and two second bar dipole magnets (232_a and 232b), a second set (S2) comprising a first bar dipole magnets (231) and two second bar dipole magnets (232_a and 232b) and a first pair (Pl) of third bar dipole magnets (23 3 _a and 233b).

Fig. 2B1-3 schematically illustrais cross-sections of a set (Sx) comprising a first bar dipole magnets (231) and two second bar dipole magnets (232_a and 232b), wherein the upmost surface of the first bar dipole magnets (231) is flush with the upmost surface of the two second bar dipole magnets (232_a and 232b), wherein Fig. 2B2 illustrâtes a method wherein the substrate (220) faces the set (Sx) and Fig. 2B3 illustrâtes a method wherein the coating layer (210) comprising the platelet-shaped magnetic or magnetîzable pigment particles faces the set (Sx). Fig. 2C1-3 and 2D1-3 schematically illustrate cross-sections of a set (Sx) comprising a first bar dipole magnets (231) and two second bar dipole magnets (232_a and 232b), wherein the upmost surface of the first bar dipole magnets (231 ) îs not flush with the upmost surface of the two second bar dipole magnets (232_a and 232b) and wherein a fourth distance (d4) is present between the upmost surface of the first bar dipole magnets (231) and the upmost surface of the two second bar dipole magnets (232_a and 232b). Fig. 2C2 and 2D2 illustrate methods wherein the substrate (220) faces the set (Sx) and Fig. 2C3 and 2D3 illustrate methods wherein the coating layer (210) comprising the platelet-shaped magnetic or magnetîzable pigment particles faces the set (Sx) of the magnetic assembly.

Fig. 3A schematically illustrâtes a top view of a magnetic assembly (300) comprising a first set (SI) comprising a first bar dipole magnets (331) and two second bar dipole magnets (332_a and 332b), a second set (S2) comprising a first bar dipole magnets (331) and two second bar dipole magnets (332_a and 332b), a third set (S3) comprising a first bar dipole magnets (331) and two second bar dipole magnets (332_a and 332b), a first pair (Pl) of third bar dipole magnets (333_a and 333b) and a second pair (P2) of third bar dipole magnets (333_a and 333b).

Fig. 3B schematically illustrâtes a cross-section of the magnetic assembly (300) of Fig. 3A in the vicinity of a cylinder, wherein the magnetic assembly (300) has been bent to match the curvature of the cylinder.

Fig. 3C schematically illustrâtes a view of the magnetic assembly (300) of Fig. 3A-B în the vicinity of a cylinder, wherein the magnetic assembly (300) has been bent to match the curvature of the cylinder.

Fig. 4 schematically illustrâtes a top view of a magnetic assembly (400) comprising a first set (SI) comprising a first bar dipole magnets (431) and two second bar dipole magnets (432_a and 432b), a second set (S2) comprising a first bar dipole magnets (431 ) and two second bar dipole magnets (432_a and 432_b), a third set (S3) comprising a first bar dipole magnets (431) and two second bar dipole magnets (432_a and 432b), a fourth set (S4) comprising a first bar dipole magnets (431) and two second bar dipole magnets (432_a and 432_b), a first pair (Pi) of third bar dipole magnets (433_a and 433b), a second pair (P2) of third bar dipole magnets (433_a and 433b) and a third pair (P3) of third bar dipole magnets (433_a and 433_b).

Fig. 5A-C schematically illustrate methods for producing an optical effect layer (OEL) on a substrate (520) according to the present invention. The method comprises a step of ii) of exposîng the coating layer to the magnetic field of the magnetic assembly (500), a further step of subsequently exposîng the coating layer to the magnetic field of a magnetic-field-generating device comprising one or more magnets (Ml), said magnets (Ml) being mounted on a rotating magnetic cylinder (560), and a step iii) of at least partially curing the radiation curable coating composition with a curing unit (550). As shown in Fig. 5A-C, an optional step (depicted with a sélective curing unit (580) in brackets) of selectively at least partially curing one or more first areas of the coating layer of step ii) so as to fix at least a part of the non-spherical magnetic or magnetizable particles in their adopted positions and orientations such that one or more second areas of the coating layer are not exposed to irradiation, may be carried out prior to the step of exposing the coating layer to the magnetic field ofthe one or more magnets (Ml) so as to reorient at least a part of the platelet-shaped magnetic or magnétisable particles in the one or more second areas.

Fig. 5D schematically illustrâtes a method for producing an optical effect layer (OEL) on a substrate (520) according to the present invention. The method comprises a step of ii) of exposing, în a single step, the radiation curable coating composition to the interaction of the magnetic fields of the magnetic assembly (500) described herein and of a magnetic-fieldgenerating device comprising one or more hard magnetic magnets (Ml) or comprising one or more soft magnetic plates (Ml) carrying one or more indicia in the form of voids and/or indentations and/or protrusions, said one or more hard magnetic magnets or soft magnetic plates (Ml ) being mounted on a rotating magnetic cylinder (560) and a step iii) of at least partially curing the radiation curable coating composition with a curing unit (550).

Fig. 5E schematîcally illustrâtes a method for producing an optical effect layer (OEL) on a substrate (520) according to the present invention. The method comprises a step of ii) of a) exposing the radiation curable coating composition to the magnetic field of a first magnetic assembly (500a) described herein; then b) exposing, in a single step, the radiation curable coating composition to the interaction of the magnetic fields of the magnetic assembly (500b) described herein and of a magnetic-field-generating device comprising one or more hard magnetic magnets (Ml) or comprising one or more soft magnetic plates (Ml) carrying one or more indicia în the form of voids and/or indentations and/or protrusions, said one or more hard magnetic magnets or soft magnetic plates (Ml) being mounted on a rotating magnetic cylinder (560) and a step iii) of at least partially curing the radiation curable coating composition with a curing unit (550). As shown in Fig. 5E, an optional step (depicted with a sélective curing unit (580) in brackets) of selectively at least partially curing one or more first areas of the coating layer of step ii) so as to fix at least a part of the non-spherical magnetic or magnetizable particles in their adopted positions and orientations such that one or more second areas ofthe coating layer are not exposed to irradiation, may be carried out prior to the single step of exposing the radiation curable coating composition to the interaction of the magnetic fields of the magnetic assembly (500b) and of the magnetic-field-generating device so as to re-orient at least a part ofthe platelet-shaped magnetic or magnétisable particles in the one or more second areas.

Fig. 5F schematîcally illustrate a method for producing an optical effect layer (OEL) on a substrate (520) according to the present invention. The method comprises a step of ii) of exposing, in a single step, the radiation curable coating composition to the interaction of the magnetic fields of a first magnetic assembly (500a) described herein and of a first magneticfield-generating device comprising one or more hard magnetic magnets (Ml a) or comprising one or more soft magnetic plates (Mla) carrying one or more indicia în the form of voids and/or indentations and/or protrusions, said one or more hard magnetic magnets or soft magnetic plates (Ml a) being mounted on a rotating magnetic cylinder (560a); a step iii) (depicted with a sélective curing unit (580)) of selectively at least partially curing one or more first areas ofthe coating layer of step ii) so as to fix at least a part of the non-spherical magnetic or magnetizable particles in their adopted positions and orientations such that one or more second areas of the coating layer are not exposed to irradiation; a step iv) of exposing the coating layer to the magnetic field of a second magnetic assembly (500b) described herein so as to biaxially re-orient the non-spherical magnetic or magnetizable particles comprised in the one or more second (not yet cured) areas of the coating layer; a step v) of exposing the radiation curable coating composition to the magnetic field of a second magnetic-field-generating device comprising one or more hard magnetic magnets (Mlb), said one or more hard magnetic magnets (Mlb) being mounted on a rotating magnetic cylinder (560b); and a step vi) of at least partially curing the radiation curable coating composition with a curing unit (550).

Fig. 5G schematically illustrate a method for producing an optical effect layer (OEL) ou a substrate (520) according to the present invention. The method comprises a step of ii) of exposing, in a single step, the radiation curable coating composition to the interaction of the magnetic fields of a first magnetic assembly (500a) described herein and of a first magneticfield-generating device comprising one or more hard magnetic magnets (Ml a) or comprising one or more soft magnetic plates (Ml a) carrying one or more indicia in the form of voids and/or indentations and/or protrusions, said one or more hard magnetic magnets or soft magnetic plates (Mla) being mounted on a rotating magnetic cylinder (560a); a step iii) (depicted with a sélective curing unit (580)) of selectively at least partially curing one or more first areas ofthe coating layer of step ii) so as to fix at least a part of the non-spherical magnetic or magnetizable particles in their adopted positions and orientations such that one or more second areas of the coating layer are not exposed to irradiation; a step iv) of exposing the coating layer to the magnetic field of a second magnetic assembly (500b) described herein so as to biaxially re-orient the non-spherical magnetic or magnetizable particles comprised în the one or more second (not yet cured) areas of the coating layer; a step v) exposing, in a single step, the radiation curable coating composition to the interaction of the magnetic fields of a third magnetic assembly (500c) described herein and of a second magnetic-field-generating device comprising one or more hard magnetic magnets (Mlb) or comprising one or more soft magnetic plates (Mlb) carrying one or more indicia in the form of voîds and/or indentations and/or protrusions, said one or more hard magnetic magnets or soft magnetic plates (Mlb) being mounted on a rotating magnetic cylinder (560) and a step vi) of at least partially curing the radiation curable coating composition with a curing unit (550).

Fig. 5H schematically illustrate a method for producing an optical effect layer (OEL) on a substrate (520) according to the present invention. The method comprises a step of ii) of a) exposing the radiation curable coating composition to the magnetic fields of a first magnetic assembly (500a) described herein; then b) exposing, in a single step, the radiation curable coating composition to the interaction of the magnetic fields of a second magnetic assembly (500b) described herein and of a first magnetic-field-generating device comprising one or more hard magnetic magnets (Ml a) or comprising one or more soft magnetic plates (Ml a) carrying one or more indicia in the form of voids and/or indentations and/or protrusions, said one or more hard magnetic magnets or soft magnetic plates (Mla) being mounted on a rotating magnetic cylinder (560a); a step iii) (depicted with a sélective curing unit (580)) of selectively at least partially curing one or more first areas of the coating layer of step ii) so as to fix at least a part of the non-spherical magnetic or magnetizable particles in their adopted positions and orientations such that one or more second areas of the coating layer are not exposed to irradiation; a step iv) of 5 exposing the coating layer to the magnetic field of a third magnetic assembiy (500c) described herein so as to biaxially re-orient the non-spherical magnetic or magnetizable particles comprised in the one or more second (not yet cured) areas of the coating layer; a step v) exposing, in a single step, the radiation curable coating composition to the interaction of the magnetic fïelds of a fourth magnetic assembiy (500d) described herein and of a second magnetic-field-generating device comprising one or more hard magnetic magnets (Mlb) or comprising one or more soft magnetic plates (Mlb) carrying one or more indicia in the form of voids and/or indentations and/or protrusions, said one or more hard magnetic magnets or soft magnetic plates (Mlb) being mounted on a rotating magnetic cylinder (560) and a step vi) of at least partially curing the radiation curable coating composition with a curing unit (550).

Fig. 6A-B schematically îllustrate a comparative method for producing an optical effect layer (OEL) on a substrate (620).

Fig. 7A-C shows pîctures of OELs prepared with the method according to the présent invention (El, E2 and E3, left) and prepared according to a comparative method (Cl, C2 and C3, right).

DETAILED DESCRIPTION

Définitions

The following définitions are to be used to înterpret the meaning of the terms discussed in the description and recited in the claims.

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

As used herein, the terms “about” and “substantially” mean that the amount or value in question may be the spécifie value designated or some other value in its neighborhood. Generally, the terms “about” and “substantially” denoting a certain value is întended to dénoté a range within ± 5% of the value. As one example, the phrase “about 100” dénotés a range of 100 ± 5, i.e. the range from 95 to 105. Generally, when the terms “about” and “substantially” str 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.

The terms “substantially parallel” refer to devîating not more than 10° from parallel alignment and the terms “substantially perpendicular” refer to devîating not more than 10° from perpendicular alignment.

As used herein, the term “and/or” means that either ail or only one of the éléments 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”.

The term “comprising” as used herein is întended 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.

The term “optical effect layer (OEL)” as used herein dénotés a coating layer that comprises oriented platelet-shaped magnetic or magnetizabie pigment particles and a binder, wherein said platelet-shaped magnetic or magnetizabie pigment particles are oriented by a magnetic field and wherein the oriented platelet-shaped magnetic or magnetizabie pigment particles are fixed/frozen in their orientation and position (i.e. after hardening/curing) so as to form a magnetically induced image.

The term coating composition refers to any composition which is capable of forming an optical effect layer (OEL) 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.

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. As used herein, the term “indicia” shall mean discontinuons layers such as patterns, including without limitation symbols, alphanumeric symbols, motifs, letters, words, numbers, logos and drawings.

The term “hardening” is used to dénoté 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 couvert 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.

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.

The term “security feature” is used to dénoté an image, pattern or graphie element that can be used for authentication purposes.

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 “prefeired” embodiments/features îs technically meanîngful.

In the context of the present text, the term “plane” covers not only fiat planes, but also curved planes such as the circumferential surface of a cylinder. In this respect a “plane” which is oriented so as to be “parallel” to a curved plane îs also curved so that the local tangents to the two planes are parallel to each other. Similarly, a direction which îs oriented so as to be perpendicular to a curved plane is perpendîcular to the tangents to tire plane in the point where it would cross the plane.

In other words, if a substrate is in an orientation substantially parallel to a curved first plane and above the first plane, it is formed so that the local tangents to the substrate in a first point thereof are parallel to the local tangents to the curved first plane in a second point thereof, wherein the first and second points are relatively positioned with respect to each other along a direction perpendicular to the local tangents in the first and second points.

The present invention provides magnetic assemblies (xOO) suitable for producing optical effect layers (OELs) on substrates (x20), wherein said OELs are based on magnetîcally oriented platelet-shaped magnetic or magnetizable pigment particles. In contrast to needle-shaped pigment particles which can be considered as one-dimensional particles,. platelet-shaped pigment parti cl es hâve an X-axis and a Y-axis defining a plane of prédominant extension of the particles. In other words, platelet-shaped pigment particles may be considered to be two-dimensional particles due to the large aspect ratio of their dimensions as can be seen in Figure 1. As shown in Figure 1, a platelet-shaped pigment particle can be considered as a two-dimensional structure wherein the dimensions X and Y are substantially larger than 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 the longest dimension Crossing the pigment particle and a second axis Y perpendicular to X which also lies within said pigment particles.

In contrast to a mono-axial orientation wherein platelet-shaped magnetic or magnetizable pigment particles are oriented in such a way that only their main axis is constrained by the magnetic field, carrying out a bi-axîal orientation means that the platelet-shaped magnetic or magnétisable pigment particles are made to orient in such a way that their two main axes are constrained. That îs, each platelet-shaped magnetic or magnétisable pigment particle can be considered to hâve a major axis in the plane of the pigment particle and an orthogonal mînor axis in the plane of the pigment particle. The major and minor axes of the platelet-shaped magnetic or magnétisable pigment particles are each caused to orient according to the magnetic field. Effectively, this results in neighboring platelet-shaped magnetic pigment particles that are close to each other in space to be essentially parallel to each other. Put another way, bi-axîal orientation aligns the planes of the platelet-shaped magnetic or magnétisable pigment particles so that the planes of said pigment particles are oriented to be essentially parallel relative to the planes of neighboring (in ail directions) platelet-shaped magnetic or magnétisable pigment particles. The magnetic assemblies (xOO) described herein allow to bi-axially orient the plateletshaped magnetic or magnetizable pigment particles described herein. By exposîng the plateletshaped magnetic or magnetizable pigment particles solely to the magnetic assemblies (xOO) described herein (i.e. no simultaneous exposure to an additional magnetic field-generating device and/or no re-orientation step), the platelet-shaped magnetic or magnetizable pigment particles form a sheet-like structure with their X and Y axes substantially parallel to the substrate (x20) surface and are planarized in said two dimensions.

The magnetic assemblies (xOO) described herein are configured for receiving the substrate (x20) described herein in an orientation substantially parallel to a first plane and substantially parallel to the substrate (x20) during the methods for producing the optical effect layers (OELs) described herein. The first plane described herein is substantially parallel to the substrate (x20) during the method described herein and is the first plane being located above the upmost surface of the two second bar dipole magnets (x32_a and x32_b) (as shown in the figures.

The magnetic assemblies (xOO) described herein comprise a) at least the first set (SI) and the second set (S2), each set (SI, S2) comprising the first bar dipole magnets (x31) and the second bar dipole magnets (x32_a and x32_b) described herein and b) the first pair (Pl) of third bar dipole magnets (x33_a and x33_b) described herein, wherein the first bar dipole magnets (x31) ofthe first and second sets (SI, S2), the second bar dipole magnets (x32_a and x32_b) of the first and second sets (SI, S2), and the third bar dipole magnets (x33_a and x33_b) are at least partially embedded in the non-magnetic supporting matrix described herein.

As shown for example in Fig. 2A, each of the first and second sets (S 1, S 2) comprises i) the first bar dipole magnet (x31) described herein and the two second bar dipole magnets (x32_a and x32_b) described herein. The bar dipole magnets (x31) of the first and second sets (SI, S2) hâve a first thickness (Ll), a first length (L4) and a first width (L5) and hâve their magnetic axes oriented to be substantially parallel to the first plane, substantially parallel to the length (L4) (and substantially parallel to the substrate (x20) during the method described herein). The first bar dipole magnets (x31) of the first and second sets (SI, S2) hâve substantially the same first length (L4) and first width (L5). The first bar dipole magnets (x31) ofthe first and second sets (SI, S2) preferably hâve substantially the same first thickness (LI) as the first bar dipole magnet (x31) of the second set (S2). The first bar dipole magnets (x31) ofthe first and second sets (SI, S2) are spaced apart by a first distance (dl). The first distance (dl) between the first bar dipole magnets (x31) ofthe first and second sets (SI, S2) is preferably greater than or equal to 15% ofthe first length (L4) and smaller than or equal to 150% of the first length (L4) (i.e. O.l5*L4<dl<1.5*L4), more preferably greater than or equal to 25% of the first length (L4) and smaller than or equal to 120% ofthe first length (L4) (i.e. 0.25*L4<dl<1.2*L4), even more preferably greater than or equal to 25% of the first length (L4) and smaller than or equal to 80% of the first length (L4) (i.e. 0.25*L4<dl<0.8*L4).

The first bar dipole magnet (x31) of the first set (SI) has a magnetic direction opposite to the magnetic direction of the first bar dipole magnet (x31 ) of the second set (S2).

The first bar dipole magnets (x31 ) of the first set (S 1 ) and of the second set (S2) may be single pièces or may be formed by two or more adjacent bar dipole magnets (x3h) having a first width (L5), a first thickness (Ll), wherein the first length (L4) described herein is the sum of ali said two or more adjacent bar dipole magnets (x31j).

The two second bar dipole magnets (x32_a andx32_b) ofthe first and second sets (SI, S2) hâve a second thickness (L2), a second length (L6) and a second width (L7) and hâve their upmost surfaces flush with each other. The two second bar dipole magnets (x32_a and x32_b) of the first and second sets (SI, S2) hâve their magnetic axes oriented to be substantially perpendicular to the first plane, substantially paraliel to their thickness (L2) (and substantially perpendicular to the substrate (x20) during the method described herein). The two second bar dipole magnets (x32_a and x32b) of the first and second sets (SI, S2) hâve substantially the same second lengths (L6) and hâve substantially the same second widths (L7). The two second bar dipole magnets (x32_a and x32b) ofthe first set (SI) preferably hâve substantially the same second thickness (L2) as the two second bar dipole magnets (x32_a and x32b) ofthe second set (S2).

For each set of the first and second sets (SI, S2), the fïrst bar dipole magnet (x31) and the second bar dipole magnets (x32_a and x32b) are aligned to form a column, in that the first bar dipole magnet (x31) of each of the first and second sets (SI, S2) is respectively placed between and spaced apart from the second bar dipole magnets (x32_a and x32b) by a second distance (d2), said second distance (d2) being substantially the same for the first and second sets (SI, S2).

For each set (S 1, S2), the North pôle of one of the second bar dipole magnets (x32_a, x32b) points towards the first plane (and points towards the substrate (x20) during the method described herein) when the North Pôle of the first bar dipole magnet (x31) points towards that second bar dipole magnet (x32_a, x32b), and the South pôle of the other of the second bar dipole magnets (x32_a, x32b) points towards the first plane (and points towards the substrate (x20) during the method described herein) when the South Pôle of the first bar dipole magnet (x31) points towards that second bar dipole magnet (x32_a, x32b).

As shown for example in Fig. 2A, the first pair (Pl) described herein comprises the third bar dipole magnets (x33_a and x33b) described herein, wherein said third bar dipole magnets (x33_aand x33b) hâve a third thickness (L3), a third length (L8) and a third width (L9) and bave their magnetic axes oriented to be substantially paraliel to the first plane (and substantially paraliel to the substrate (x20) during the method described herein).

The second widths (L7) of the two second bar dipole magnets (x32_a and x32b) of the first and second sets (S 1, S2) hâve substantially the same value as the third width (L9) of the third bar dipole magnets (x33_a and x33b).

Each of the third bar dipole magnets (x33_a and x33b) is aligned with one second bar dipole magnet (x32_a and x32b) of the first set (SI) and one second bar dipole magnet (x32_a and x32b) of the second set (S2) so as to form two lines, the third bar dipole magnets (x33_a and x33b) being placed between and spaced apart from the respective second bar dipole magnets (x32_a and x32b) by a third distance (d3), said third distance (d3) being substantially the same for the two lines. The North pôles of the third bar dipole magnets (x33_a and x33b) respectively point towards one of the second bar dipole magnets (x32_a and x32b) and the North Pôles of said ones of the second bar dipole magnets (x32_a and x32b) point towards the first plane (and point towards the substrate (x20) during the method described herein); or the South pôles of the third bar dipole magnets (x33_a and x33b) respectiveîy point towards one of the second bar dipole magnets (x32_a and x32b) and the South Pôles of said ones of the second bar dipole magnets (x32_a and x32b) point towards the first plane (and point towards the substrate (x20) during the method described herein). According to a preferred embodiment shown for example in Fig. 2A, 3 and 4, the magnetic assembly (xOO) described herein is rectangular shaped, in particular square shaped, when observed from a top view. The rectangular shaped, in particular square shaped, magnetic assembly (xOO) is thus delimited by the two columns formed by the first and second sets (SI, S2) and the two lines in Fig. 2A; or by the two columns ofthe first and third set (SI, S3) and the two lines in Fig. 3; or by the two columns of the first and fourth sets (SI, S4) and the two lines in Fig. 4.

The first thickness (L 1 ) of the first bar dipole magnets (x31 ) of the first and second sets (SI, S2) is preferably equal to or smaller than the second thickness (L2) ofthe second bar dipole magnets (x32_a and x32b) of the first and second sets (SI, S2). More preferably, the ratio ofthe second thickness (L2) ofthe second bar dipole magnets (x32_a and x32b) ofthe first and second sets (SI, S2) over the first thickness (Ll ) of the first bar dipole magnets (x31) of the first and second sets (SI, S2) (L2/L1) is equal to or smaller than 3 and greater than or equal to 1 (i.e. 1 < L2/L1 < 3), even more preferably equal to or smaller than 2.5 and greater than or equal to 1.5 (i.e. 1.5 < L2/L1 < 2.5).

The first thickness (Ll) of the first bar dipole magnets (x31) ofthe first and second sets (SI, S2) is preferably equal to or smaller than the third thickness (L3) of the third bar dipole magnets (x33_a and x33b) of the first pair (P 1 ). More preferably, the ratio of the third thickness (L3) ofthe third bar dipole magnets (x33_a and x33b) ofthe first pair (Pl) over the first thickness (Ll) ofthe first bar dipole magnets (x31) ofthe first and second sets (SI, S2) (L3/L1) is equal to or smaller than 3 and greater than or equal to 1 (i.e. 1 < L3/L1 < 3), even more preferably equai to or smaller than 2.5 and greater than or equal to 1.5 (i.e. 1.5<L3/L1 < 2.5).

The second distance (d2) between the first bar dipole magnet (x31 ) and the second bar dipole magnets (x32_a and x32b) is larger than or equal to 0 and smaller than or equal to % of the first thickness (Ll) of the first bar dipole magnets (x31) (i.e. 0 < d2 < %L1).

The third distance (d3) between the third bar dipole magnets (x33_a and x33b) of the first pair (P 1 ) and the second bar dipole magnets (x32_a and x32b) of the first and second sets (SI, S2) is larger than or equal to 0 and smaller than or equal to the % of the first thickness (Ll) of the first bar dipole magnets (x31) (i.e. 0 < d3 < %L1).

As shown in Fig. 2A, the first distance (dl) between the first bar dipole magnets (x31) of the first and second sets (S 1, S2) consists of the sum of the third length (L8) of one of the third bar dipole magnets (x33_a and x33b) and the two third distances (d3) between the third bai' dipole magnets (x33_a and x33b) and the second bar dipole magnets (x32_a and x32b).

According to one embodiment shown for example in Fig. 2A and 2B1-B3, the upmost surface of the first bar dipole magnets (x31) of the first and second sets (SI, S2) is flush with the upmost surface of the second bar dipole magnets (x32_a and x32b) of the first and second sets (S 1, S2). The upmost surface of the first bar dipole magnets (x31 ) of the first and second sets (SI, S2) is preferably flush with the upmost surface of the second bar dipole magnets (x32_a and x32b) of the first and second sets (S 1, S2) and also flush with the upmost surface of the third bar dipole magnets (x33_a and x33b).

According to another embodiment shown for example in Fig. 2C1-2D3, the upmost surface of the first bar dipole magnets (x31 ) of the first and second sets (S 1, S2) is not flush with the upmost surface of the second bar dipole magnets (x32_a and x32b) of the first and second sets (S 1, S2) and there is a fourth distance (d4) between the upmost surface of the first bar dipole magnets (x31) of the first and second sets (S 1, S2) and the second bar dipole magnets (x32_a and x32b) ofthe first and second sets (Si, S2).

According to this embodiment, the absolute value of the fourth distance (d4) between the upmost surface of the first bar dipole magnets (x31 ) of the first and second sets (SI, S2) and the second bar dipole magnets (x32_a and x32b) of the first and second sets (SI, S2) is larger than 0 and smaller than or equal to half of the first thickness (Ll) ofthe first bar dipole magnets (x31) (i.e. 0 < |d4] < % Ll).

According to one embodiment, the magnetic assemblies (xOO) may further comprise one or more combinations comprising i) (2+i)th set (Sp+i)) such as those described for the first and second sets (SI, S2) and correspondingly ii) an additional (l+i)th pair (Pi+i) (such as those described herein), wherein i = 1, 2, etc.

For each combination described herein, the (2+i)th set (S(2+i)) comprises one further first bar dipole magnet (x31) having the first thickness (Ll), the first length (L4) and the first wîdth (L5), and having its magnetic axis oriented to be substantially parallel to the first plane, and two further second bar dipole magnets (x32_a and x32b) having the second thickness (L2), the second length (L6) and the second width (L7), the two second bar dipole magnets (x32_a, x32b) having their upmost surfaces flush with each other, and having their magnetic axes oriented to be substantially perpendicular to the first plane, the first bar dipole magnet (x31) of the (2+î)th set (Ss+i) having a magnetic direction opposite to the magnetic direction of the first bar dipole magnet (x31 ) of the (2+î-l)th set (S2+i-i); the first bar dipole magnets (x31 ) of the (2+i)th and (2+i-1 )th sets (S2+1, S2+i-i) being spaced apart by the first distance (dl); the first bar dipole magnet (x31) ofthe

IS (2+i)th set (S2+O having substantially the same length (L5) and width (L4) as·the first bar dipole magnet (x31) of the (2+i-l )th set (S2-H-1); and the two second bar dipole magnets (x32_a, x32b) ofthe (2+i)th set (S2+O having substantially the same lengths (L6) and widths (L7) as the two second bar dipole magnets (x32_a, x32b) of the (2+i-1 )th set (S2+1-1); the first bar dipole magnet (x31 ) and the second bar dipole magnets (x32_a, x32b) being aligned to form a column, in that the first bar dipole magnet (x31 ) of the (2+i)th set (S2+1) is placed between and spaced apart from the second bar dipole magnets (x32_a, x32b) by the second distance (d2); the first and second lengths (L4 and L6) being substantially the same; the North pôle of one of the second bar dipole magnets (x32_a, x32b) of the (2+i)th set (S2+O poînting towards the first plane and the North Pôle of the first bar dipole magnet (x31 ) pointing towards that second bar dipole magnet, and the South pôle of the other of the second bar dipole magnets (x32_a, x32b) of the (2+i)th set (S2+1) pointing towards the first plane and the South Pôle of the first bar dipole magnet (x31) pointing towards that second bar dipole magnet.

For each combination described herein, the (1 +i)th pair (Pi+i) comprises the third bar dipole magnets (x33_a and x33t) having the third thickness (L3), the third length (L9) and the third width (L8) and having their magnetic axes oriented to be substantially parallel to the magnetic axes of the third bar dipole magnets (x33_a and x33b) of the (1 +i-1 )th pair (P₁₊ra).

As shown in Fig. 3, the magnetic assemblies (xOO) may further comprise one or more combinations comprising c) a third set (S3) (i.e. a (2+i)th set with i = 1) a such as those described herein and d) an additional second pair (P2) ((i.e. a ((l+i)thpair with i = 1) such as those described herein. As shown for example in Fig. 3, the magnetic assemblies (xOO) may further comprise c) a third set (S3), said third set (S3) comprising i) a further first bar dipole magnet (x31) and ii) two further second bar dipole magnets (x32_a and x32b) and d) a second pair (P2), said second pair (P2) comprising two further third bar dipole magnets (x33_a and x33b), wherein the first bar dipole magnets (x31 ) of the third set (S3), the second bar dipole magnets (x32_a and x32b) of the third set (S3) and the third bar dipole magnets (x33_a and x33b) ofthe second pair (P2) are at least partially embedded in the non-magnetic supporting matrix described herein (not shown in Fig. 3).

The first bar dipole magnet (x31) of the third set (S3) has the first thickness (Ll), the first length (L4) and the first width (L5). The second bar dipole magnets (x32_a and x32b) of the third set (S3) hâve the second thickness (L2), the second length (L6) and the second width (L7) and hâve their upmost surfaces flush with each other.

The first bar dipole magnet (x31) of the third set (S3) has its magnetic axis oriented to be substantially parallel to the first plane (and substantially parallel to the substrate (x20) during the method described herein). The first bar dipole magnet (x31) of the third set (S3) has a magnetic direction opposite to the magnetic direction of the first bar dipole magnet (x3I) ofthe second set (S2), The second bar dipole magnets (x32_a and x32b) of the third set (S3) hâve their magnetic axes oriented to be perpendicular to the first plane (and substantially perpendicular to the substrate (x20) during the method described hsein).

Tlie first bar dipole magnets (x31) of the third and second sets (S3, S2) are spaced apart by the first distance (dl), said first distance (dl) being substantially the same as the first distance (dl) for the first and second sets (SI, S2).

The first bar dipole magnet (x31 ) of the third set (S 3) has substantially the same first length (L4) and first width (L5) as the first bar dipole magnet (x31) of the second set (S2) and the two second bar dipole magnets (x32_a, x32b) ofthe third set (S3) bave substantially the same second lengths (L6) and second widths (L7) as the two second bar dipole magnets (x32_a, x32b) of the second set (S2). The first width (L5) of the first bar dipole magnet (x31) of the third set (S3) and second lengths (L6) of second bar dipole magnets (x32_a and x32b) of the third set (S3) are substantially the same.

The first bar dipole magnet (x31) and the second bar dipole magnets (x32_a, x32b) of the third set (S3) are alîgned to form a column, in that the first bar dipole magnet (x31) of the third set (S3) is placed between and spaced apart from the second bar dipole magnets (x32_a, x32b) of the third set (S3) by the second distance (d2), said second distance (d2) being substantially the same as the second distance (d2) for the first and second sets (SI, S2).

Tle North pôle of one of the second bar dipole magnets (x32_a, x32b) of the third set (S3) points towards the first plane (and points towards the substrate (x20) during the method described herein) and the North Pôle of the first bar dipole magnet (x31) points towards that second bar dipole magnet (x32_a, x32b). The South pôle of the other of the second bar dipole magnets (x32_a, x32b) of the third set (S3) points towards the first plane (and points towards the substrate (x20) during the method described herein) and the South Pôle of the fiist bar dipole magnet (x31) points towards that second bar dipole magnet (x32_a, x32b). The third bar dipole magnets (x33_a and x33b) of the second pair (P2) hâve the third thickness (L3), the third length (L8) and the third width (L9) and hâve their magnetic axes oriented to be parallel to the magnetic axes of the third bar dipole magnets (x33_a and x33b) of the first pair (Pl) (and substantially parallel to the first plane and substantially parallel to the substrate (x20) during the method described herein).

Each of the third bar dipole magnets (x33_a andx33b) of the second pair (P2) is aligned with one second bar dipole magnet (x32_a and x32b) of the third set (S3) and one second bar dipole magnet (x32_a and x32b) of the second set (S2) so as to form two lines, the third bar dipole magnets (x33_a and x33b) being placed between and spaced apart from the respective second bar dipole magnets (x32_a and x32b) by the third distance (d3), the third distance (d3) being substantially the same as the third distance (d3) described herein. The North pôles ofthe third bar dipole magnets (x33_a and x33b) ofthe second pair (P2) respectively point towards one of the second bar dipole magnets (x32_a and x32b) of the third and second sets (S3, S2) and the North Pôles of said one of the second bar dipole magnets (x32_a and x32b) point towards the first plane (and point towards to the substrate (x20) during the method described herein); or the South pôles of the third bar dipole magnets (x33_a and x33b) of the second pair (P2) respectively point towards one of the second bar dipole magnets (x32_a and x32b) of the third and second sets (S3, S2) and the South Pôles of said ones of the second bar dipole magnets (x32_a and x32b) point towards the first plane (and point towards to the substrate (x20) during the method described herein).

As shown in Fig. 4, the magnetic assemblies (xOO) may further comprise one or more combinations comprising i) a fourth set (S₄) (i.e. a (2+i)th set with Î = 2) a such as those described herein and an additional third pair (P3) ((i.e. a ( 1 +i)th pair with i = 2) such as those described herein. As shown for example in Fig. 4, the magnetic assemblies (xOO) may further comprise c) the third set (S3) described hereabove and a fourth set (S4), said a fourth set (S4) comprising i) a further first bar dipole magnet (x31 ) and ii) two further second bar dipole magnets (x32_a and x32b), d) the second pair (P2) described herein and a third pair (P3), said third pair (P3) comprising third bar dipole magnets (x33_a and x33b), wherein the first bar dipole magnets (x31) ofthe fourth set (S4), the second bar dipole magnets (x32_a and x32b) of the a fourth set (S4), and the third bar dipole magnets (x33_aand x33b) of the third pair (P3) are at least partially embedded in the non-magnetîc supporting matrix described herein (not shown in Fig. 4).

The first bar dipole magnet (x31) of the fourth set (S4) has the first thickness (Ll), tire first length (L4) and the first width (L5). The second bar dipole magnets (x32_a and x32b) of the fourth set (S4) hâve the second thickness (L2), the second length (L6) and the second width (L7) and hâve their upmost surfaces flush with each other.

The first bar dipole magnet (x31 ) of the fourth set (S4) has its magnetic axis oriented to be substantially parallel to the first plane (and substantially parallel to the substrate (x20) during the method described herein). The first bar dipole magnet (x31) ofthe fourth set (S4) has a magnetic direction opposite to the magnetic direction of the first bar dipole magnet (x31 ) of the third set (S3). The second bar dipole magnets (x32_a and x32_b) of the fourth set (S4) hâve their magnetic axes oriented to be perpendicular to the first plane (and substantially perpendicular to the substrate (x20) during the method described herein).

The first bar dipole magnets (x31 ) of the fourth and third sets (S4, S3) are spaced apart by the first distance (dl), said first distance (dl) being substantially the same as the first distance (dl) for the first and second sets (SI, S2) and substantially the same as the first distance (dl) for the second and third sets (S2, S3).

The first bar dipole magnet (x31 ) of the fourth set (S4) has substantially the same first length (L4) as the second length (L6) of the second bar dipole magnets (x32_a and x32_b) of the fourth set (S4) and as the second length (L6) of the second bar dipole magnets (x32_aand x32_b) ofthe third set (S3), ofthe second set (S2) and ofthe first set (SI).

The first bar dipole magnet (x31 ) of the fourth set (S4) has substantially the same first length (L4) and first width (L5) as the first bar dipole magnet (x31) ofthe third set (S3), as the first bar dipole magnet (x31 ) of the second set (S2) and as the first bar dipole magnet (x31) of the first set (SI).

The two second bar dipole magnets (x32_a, x32_b) of the fourth set (S4) hâve substantially the same second lengths (L6) and second widths (L7) as the two second bar dipole magnets (x32_a, x32_b) of the third set (S 3), as the two second bar dipole magnets (x32_a, x32_b) of the second set (S2) and as the two second bar dipole magnets (x32_a, x32_b) of the first set (SI).

The first width (L5) of the first bar dipole magnet (x31) of the fourth set (S4) and second lengths (L6) of second bar dipole magnets (x32_a and x32_b) of the fourth set (S4) are substantially the same.

The first bar dipole magnet (x31 ) and the second bar dipole magnets (x32_a, x32_b) of the fourth set (S4) are aligned to form a column, in that the first bar dipole magnet (x31) of the fourth set (S4) is placed between and spaced apart from the second bar dipole magnets (x32_a, x32_b) by the second distance (d2), said second distance (d2) being substantially the same as the second distance (d2) for the first and second sets (S 1, S2) and for the second and third sets (S2, S3).

The North pôle of one of the second bar dipole magnets (x32_a, x32_b) of the fourth set (S4) points towards the first plane (and points towards the substrate (x20) during the method described herein) and the North Pôle of the first bar dipole magnet (x31) points towards that second bar dipole magnet. The South pôle of the other of the second bar dipole magnets (x32_a, x32b) of the fourth set (S4) points towards the first plane (and pointstowards the substrate (x20) during the method described herein) and the South Pôle of the first bar dipole magnet (x31) points towards that second bar dîpole magnet (x32_a, x32b). The third bar dipole magnets (x33_a and x33_b) of the third pair (P3) hâve the third thickness (L3), the third length (L8) and the third width (L9) and hâve their magnetic axes oriented to be substantially parallel to the magnetic axes of the third bar dipole magnets (x33_a and x33_b) ofthe first pair (Pl) and be substantially parallel to the magnetic axes of the third bar dipole magnets (x33_a and x33b) of the second pair (P2) (and substantially parallel to the first plane and substantially parallel to the substrate (x20) during the method described herein).

Each ofthe third bar dipole magnets (x33_a and x33_b) of the third pair (P3) is aligned with one second bar dipole magnet (x32_a and x32_b) of the fourth set (S4) and one second bar dipole magnet (x32_a and x32_b) of the third set (S3) so as to form two lines, the third bar dipole magnets (x33_a and x33_b) being placed between and spaced apart from the respective second bar dipole magnets (x32_a and x32_b) by the third distance (d3), the third distance (d3) being substantially the same as the third distance (d3) described herein. The North pôles of the third bar dipole magnets (x33_a and x33_b) of the third pair (P3) respectively point towards one of the second bar dipole magnets (x32_a and x32_b) of the fourth and third sets (S4, S3) and the North Pôles of said ones of the second bar dîpole magnets (x32_a and x32_b) of the third pair (P3) point towards the first plane (and point towards to the substrate (x20) during the method described herein); or the South pôles of the third bar dipole magnets (x33_a and x33_b) of the third pair (P3) respectively point towards one of the second bar dipole magnets (x32_a and x32_b) of the fourth and third sets (S4, S3) and the South Pôles of said ones of the second bar dipole magnets (x32_a and x32_b) pointing towards the first plane (and point towards to the substrate (x20) during the method described herein).

The top surface of the magnetic assemblies (xOO) described herein and comprising the first bar dipole magnets (x31), the second bar dipole magnets (x32_a and x32_b) and the third bar dipole magnets (x33_a and x33_b) described herein may be fiat and may be curved. For embodiments wherein the magnetic assembly (xOO) is used în the vicinity of a cylinder (see for example Fig. 5B-G), the top surface of said assemblies (xOO) is curved to match the curvature of the cylinder (see for example Fig. 3 B and 3C) and the curvature ofthe substrate (x20) carrying the coating layer (xlO), wherein the curvature ofthe magnetic assembly (xOO) is obtained by bending said assembly. For embodiments wherein the top surface of the assembly (xOO) is curved, ail tire référencés directed to the

- first plane described herein and the orientation of the magnetic axis (substantially parallel/perpendicular to the first plane) described herein correspond to the magnetic assembly that has been flattened (i.e. its configuration before its bend). For embodiments wherein the top surface ofthe assembly (xOO) is curved, the magnetic assembly (xOO) is arranged around the first cylindrical plane so that the first width (L5) of the bar dipole magnets (x31), the second length (L6) of the two second bar dipole magnets (x32a and x32b) and the third length (L8) of the third bar dipole magnets (x33a and x33b) are essentially perpendicular to the rotational axis of the cylinder and the centers of (L5), (L6) and (L8) are essentially tangential to the cylinder surface. In these embodiments, the magnetic assembly (xOO) forms a polyhedral surface around the curved first plane and around the cylinder. In these embodiments, the distance d3 correspond to the minimum distance between the respective sides of the two second bar dipole magnets (x32a or x32b) and the third bar dipole magnets(x33a or x33b).

The materials of the first bar dipole magnets (x31) of the sets (SI, S2, etc.) described herein, of the second bar dipole magnets (x32_a and x32b) of the sets (SI, S2, etc.) described herein, ofthe third bar dipole magnets (x33_a and x33_b) of the pair(s) (Pl, etc.) described herein as well as the first distance (d 1 ), the second distance (d2), the third distance (d3), the fourth distance (d4) and distance (h) are selected such that the magnetic field resulting from the magnetic field produced by the magnetic assembly (xOO) described herein is suitable for bi-axially orienting at least a part of the platelet-shaped magnetic or magnétisable pigment particles described herein to hâve both their X-axes and Y-axes substantially paraliel to the substrate surface.

The first bar dipole magnets (x31) of the sets (SI, S2, etc.) described herein, the second bar dipole magnets (x32_a and x32b) ofthe sets (SI, S2, etc.) described herein, the third bar dipole magnets (x33_a and x33b) of the pair(s) (Pl, etc.) described herein are preferably independently made of high-coercivity materials (also referred as strong magnetic materials). Suitable highcoercivity materials are materials having a maximum value of energy product (BH)_oaï of at least 20 kJ/m³, preferably at least 50 kJ/m³, more preferably at least 100 kJ/m³, even more preferably at least 200 kJ/m³. They are preferably made of one or more sintered or polymer bonded magnetic materials selected from the group consisting of Alnicos such as for example Alnico 5 (Rl-1-1), Alnico 5 DG (R 1 -1 -2), Alnico 5-7 (Rl-1-3), Alnico 6 (Rl-1-4), Alnico 8 (Rl-1-5), Alnico 8 HC (Rl-1-7) and Alnico 9 (Rl-I-6); hexaferrites of formula MFe_!2Oi9, (e.g. strontium hexaferrite (SrO*6Fe₂Os) or barium hexaferrites (BaO*6Fe2Os)), hard ferrites of the formula MFe₂Ü4 (e.g. as cobalt ferrite (CoFe₂Û4) or magnetite (FejCU), wherein M is a bivalent métal ion), ceramic 8 (SI-1-5); rare earth magnetic materials selected from the group comprising

REC.O5 (with RE = Sm or Pr), RE2TM17 (with RE = Sm, TM = Fe, Cu, Co, Zr, Hf), RE2TMJ4B (with RE = Nd, Pr, Dy, TM = Fe, Co); anisotropic alloys of Fe Cr Co; materials selected from the group ofPtCo, MnAlC, RE Cobalt 5/16, RE Cobalt 14. Preferably, the high-coercivity materials ofthe bar dipole magnets are selected from the groups consisting ofrare earth magnetic materials, and more preferably from the group consisting of Nd₂Fei4B and SmCo₅. Particularly preferred are easîly workable permanent-magnetic composite materials that comprise a permanent-magnetic filler, such as strontium-hexaferrite (SrFei₂0i9) or neodymiumiron-boron (Nd₂Fei₄B) powder, in a plastic- or rubber-type matrix. The first bar dipole magnets (x31), the second bar dipole magnet (x32_a and x32_b) and the third bar dipole magnets (x33_a and x33b) may be made of one or more different materials or may be made of the same materials. The first bar dipole magnets (x31) of the sets (SI, S2, etc.) described herein, the second bar dipole magnets (x32_a and x32_b) ofthe sets (SI, S2, etc.) described herein and the third bar dipole magnets (x33_a and x33_b) ofthe pair(s) (Pl, etc.) described herein are ai least partially embedded in the non-magnetic supporting matrix described herein, wherein said supporting matrix is used for holding the bar dipole magnets (x31, x32_a, x32_b, x33_a, x33_b) described herein together. The non-magnetic supporting matrix described herein is made of one or more non-magnetic materials. The non-magnetic materials are preferably selected from the group consisting of nonmagnetic metals and engineering plastics and polymers. Non-magnetic metals include without limitation aluminum, aluminum alloys, brasses (alloys of copper and zinc), titanium, titanium alloys and austenitic steels (i.e. non-magnetic steels). Engineering plastics and polymers include without limitation polyaryletherketones (PAEK) and its dérivatives polyetheretherketones (PEEK), polyetherketoneketones (PEKK), polyetheretherketoneketones (PEEKK) and polyetheiketoneetherketoneketone (PEKEKK); polyacetals, polyamides, polyesters, polyethers, copolyetheresters, poiyimides, polyetherimides, high-densîty polyethylene (HDPE), uhra-high molecular weight polyethylene (UHMWPE), polybutylene terephthalate (PBT), polypropylene, acrylonitrile butadiene styrene (ABS) copolymer, fluorinated and périluorinated polyethylenes, polystyrènes, polycarbonates, polyphenylenesulfide (PPS) and liquid crystal polymers. Preferred materials are aluminum alloys, PEEK (polyetheretherketone), POM (polyoxymethylene), PTFE (polytetrafluoroethylene), Nylon® (polyamide) and PPS.

Also described herein are printing apparatuses comprising the magnetic assembly (xOO) described herein and a transferring device (x70), said transferring device allowing the substrate (x20) comprising the radiation curable coating composition comprising the platelet-shaped magnetic or magnétisable pigment particles described herein to be transferred or conveyed in the vicinity of and on top of the magnetic assembly (xOO) described herein so as to bi-axially orient at least a part of the platelet-shaped magnetic or magnétisable pigment particles and also provides a constant distance between the substrate (x20) and the magnetic assembly (xOO).

The transferring device described herein consists of a substrate guiding system, preferably selected from the group consisting of chains, belts, cylinders and combinations thereof. The belts described herein may comprise magnets mounted thereon (referred in the art as linear magnetic transferring devices). The belts described herein preferably comprise grippers. The cylinders described herein are rotating cylinders (x60, x70) which may comprise hard magnetic magnets (Ml) mounted thereon (referred in the art as rotating magnetic orienting cylînder) or soft magnetic plates (Ml) carrying one or more indicia in the form of voids and/or indentations and/or protrusions.

For embodiments of methods wherein a single magnetic assembly (xOO) is used as shown for example in Fig. 5A-D, said magnetic assembly (xOO) herein may be mounted in the vicinity of the transferring device described herein, wherein said transferring device is preferably a belt comprising grippers (see for example Fig. 5A) or is mounted in the vicinity of the transferring device described herein, wherein said transferring device is preferably a rotating cylinder (x60, x70 and x70-b) (see fig. 5B-D).

For embodiments of methods wherein several magnetic assemblies (xOOa, xOOb, etc.), i.e. a first magnetic assembly (xOOa), a second magnetic assembly (xOOb), etc., are independently used as shown for example in Fig. 5E-H, the first magnetic assembly (xOOa) described herein is mounted in the vicinity of the transferring device described herein, wherein said transferring device is preferably a belt comprising grippers (see Fig. 5E and 5 H) or mounted in the vicinity of a rotating cylinder (x60) (see Fig. 5F and 5G), while further magnetic assemblies (xOOb, xOOc, etc.) are mounted in the vicinity of a transferring device such as those described herein, wherein said transferring device preferably being a rotating cylinder (x70) (see Fig. 5F, 5G and 5H) or a rotating magnetic cylinder (x60) (see Fig. 5E, 5G and 5H).

For embodiments wherein the magnetic assembly (xOO) is used in the vicinity of a rotating cylinder (see for example Fig. 5B-H), the top surface of said assemblies (xOO) is preferably curved to match the curvature of the cylinder (see for example Fig. 3 B and 3C) and the curvature ofthe substrate (x20) carrying the coating layer (xlO), it is preferred that the ratio between the diameter ofthe cylinder and the first width (L4) of the first bar dipole magnets (x31) is greater to or equal to about 5.

As shown for example in Fig. 2A and 5A-H, the printing apparatuses described herein may further comprise a curing unit (x50). Suitable curing units include equipments for UV-visible curing units comprising 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 actinie radiation.

As shown for example in Fig. 5A-C and 5E-5H, the printing apparatuses described herein may further comprise one or more sélective curing units (x80). Sélective curing allows the production of optical effect layers (OELs) exhibiting a motif made of at least two areas, wherein said two areas hâve two different magnetic orientation patterns. The one or more sélective curing units (x80) may comprise one or more fixed or removable photomasks including one or more voîds corresponding to a pattern to be formed as a part of the coating layer. The one or more sélective curing units (x80) may be addressable such as the scanning laser beam disclosed in EP 2 468 423 Al, an array of light-emitting diodes (LEDs) disclosed in WO 2017/021504 Al or an actinie radiation LED source (x41) comprising an array of individually addressable actinie radiation emitters disclosed in the co-pending patent application PCT/EP2019/087072.

The printing apparatuses described herein may further comprise a coating or printing unit for applying the radiation curable coating composition comprising the non-spherical magnetic or magnetizable pigment particles described herein on the substrate described herein. The printing unit may be a screen printing unît, a rotogravure printing unit, a fiexography printing unit, an inkjet printing unit, an intaglio printing unit (also referred in the art as engraved copper plate printing and engraved Steel die printing) or a combination thereof.

The printing apparatuses described herein may further comprise a substrate feeder so that the substrate (x20) is fed by said substrate feeder under the form of sheets or a web.

The present invention provides methods for producing optical effect layers (OEL) on substrates. The method described herein comprises a step i) of applying onto the substrate (x20) surface described herein the radiation curable coating composition comprising the platelet-shaped magnetic or magnetizable pigment particles described herein so as to form the coating layer (xlO) described herein, said composition being in a first liquid state which allows its application as a layer and which is in a not yet cured (i.e. wet) state wherein the platelet-shaped magnetic or magnetizable pigment particles can move and rotate within the composition. Since the radiation curable coating composition described herein is to be provided on a substrate (x20) surface, the radiation curable coating composition comprises at least a binder material such as those described herein and the platelet-shaped magnetic or magnetizable pigment particles, wherein said composition is in a form that allows its processing on the desired printing or coating equipment. Preferably, said step i) is carried out by a printing process, preferably selected from the group consisting of screen printing, rotogravure printing, fiexography printing, inkjet 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 intaglio printing, screen printing, rotogravure printing and flexography printing and still more preferably selected from the group consisting of screen printing, rotogravure printing and flexography printing.

The radiation curable coating composition described herein as well as the coating layer (xlO) described herein comprise the platelet-shaped magnetic or magnetizabie pigment particles described herein preferably 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 ofthe radiation curable coating composition or the coating composition.

The platelet-shaped magnetic or magnetizabie pigment particles described herein hâve, due to their non-spherical shape, non-isotropic reflectivity with respect to incident electromagnetic radiation for which the hardened/cured binder materiai is at least partially transparent. As used herein, the term “non-isotropic reflectivity” dénotés 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 ofthe 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.

The OEL described herein comprises platelet-shaped magnetic or magnetizabie pigment particles that, due to their shape, hâve non-isotropic reflectivity. In the OELs described herein, the platelet-shaped magnetic or magnetizabie pigment particles described herein are dispersed in the coating composition comprising a cured binder materiai that fixes the orientation of the plateletshaped magnetic or magnetizabie pigment particles. The binder materiai is at least in its cured 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 materiai in its cured or solid state and their orientation-dependent reflectivity can be perceived through the binder materiai at some wavelengths within this range. Preferably, the cured binder materiai is at least partially transparent to electromagnetic radiation of a range of wavelengths comprised between 200 nm and S00 nm, more preferably comprised between 400 nm and 700 nm. Herein, the term “transparent” dénotés that the transmission of electromagnetic radiation through a layer of 20 pm of tire hardened binder materiai as present in the OEL (not including the platelet-shaped magnetic or magnetizabie pigment particles, but ail other optîonal 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 platelet-shaped magnetic or magnetizable pigment particîes) in accordance with well-established test methods, e.g. DIN 5036-3 (1979-11). If the OEL serves as a covert security feature, then 5 typically technical means will be necessary to detect the (complété) optical effect generated by the OEL under respective illuminating conditions comprising the selected non-visible wavelength; said détection requiring that the wavelength of incident radiation is selected outside the visible range, e.g. in the near UV-range.

Suitable examples of platelet-shaped magnetic or magnetizable pigment particîes described 10 herein include without limitation pigment particîes comprising a magnetic métal selected from the group consisting of cobalt (Co), iron (Fe), and nickel (Ni); a magnetic alloy of iron, manganèse, cobalt, nickel or a mixture of two or more thereof; a magnetic oxide of chromium, manganèse, 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, manganèse, 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 hématite (Fe2O₃), magnetite (Fe₃O4), chromium dioxide (CrO₂), magnetic ferrites (MFe2O₄), magnetic spinels (MR2O4), magnetic hexaferrites (MFejzOïe), magnetic orthoferrites (RFeO₃), magnetic gamets M₃R₂(AO4)3, wherein M stands for two-valent métal, R stands for three-valent métal, and A stands for four-valent métal.

Examples of platelet-shaped magnetic or magnetizable pigment particîes described herein include without limitation pigment particîes comprising a magnetic layer M made from one or more of a magnetic métal such as cobalt (Co), iron (Fe), or nickel (Ni); and a magnetic alloy of 25 iron, cobalt or nickel, wherein said magnetic or magnetizable pigment particîes 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 métal fluorides such as magnésium fiuoride (MgF₂), Silicon oxide (SiO), Silicon dioxide (SiO₂), titanium oxide (T1O2), and aluminum oxide (AI2O3), more preferably Silicon 30 dioxide (SiO₂); or layers B independently made from one or more selected from the group consisting of metals and métal alloys, preferably selected from the group consisting of refiective metals and refiective métal 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 35 B such as those described hereabove. Typical examples of the platelet-shaped magnetic or magnetîzable 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, 5 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.

The radiation curable coating composition described herein may comprise platelet-shaped optically variable magnetic or magnetîzable pigment particles, and/or platelet-shaped magnetic 10 or magnetîzable pigment particles having no optically variable properties. Preferably, at least a part ofthe platelet-shaped magnetic or magnetîzable pigment particles described herein is constituted by platelet-shaped optically variable magnetic or magnetîzable pigment particles. In addition to the overt security provided by the colorshifling property of the optically variable magnetic or magnetîzable pigment particles, which allows easily detecting, recognizing and/or 15 discriminating an article or security document carrying an ink, coating composition, or coating layer comprising the optically variable magnetic or magnetîzable pigment particles described herein from their possible counterfeits using the unaided human senses, the optical properties of the optically variable magnetic or magnetîzable pigment particles may also be used as a machine readable tool for the récognition of the OEL. Thus, the optical properties of the optically variable 20 magnetic or magnetîzable pigment particles may simultaneously be used as a covert or semicovert security feature in an authenti cation process wherein the optical (e.g. spectral) properties of the pigment particles are analyzed.

The use of platelet-shaped optically variable magnetic or magnetîzable pigment particles in coating layers for producing an OEL enhances the significance of the OEL as a security feature 25 in security document applications, because such materials are reserved to the security document printing industry and are not commercially available to the public.

As mentioned above, preferably at least a part of the platelet-shaped magnetic or magnetîzable pigment particles is constituted by platelet-shaped optically variable magnetic or magnetîzable pigment particles. These are more preferably selected from the group consisting of magnetic 30 thin-film interférence pigment particles, magnetic cholesteric liquid crystal pigment particles, interférence coated pigment particles comprising a magnetic material and mixtures of two or more thereof.

Magnetic thin film interférence 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 Bl; WO 2003/000801 A2;

US 6,838,166; WO 2007/131833 Al; EP 2 402 401 Bl; WO 2019/103937 Al; WO .2020/006286 Al and in the documents cited thereîn. Preferably, the magnetic thin film interférence 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 pigments particles having a multilayer structure combining one or more multilayer Fabry-Perot structures. 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). Preferred six-layer Fabry-Perot multilayer structures consist of absorber/dielectric/reflector/magnetic/dielectric/absorber multilayer structures.

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.

Preferred pigments particles having a multilayer structure combining one or more Fabry-Perot structures are those described in WO 2019/103937 Al 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 Al and EP 3 587 500 Al disclose further preferred pigment particles having a multilayer structure.

Preferably, the reflector layers described herein are independently made from one or more selected from the group consisting of metals and métal alloys, preferably selected from the group consisting of reflectîve metals and reflective métal 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 métal fluorides such as magnésium fluoride (MgF2), aluminum fluoride (AIF3), cérium fluoride (CeFs), lanthanum fluoride (LaF₃), sodium aluminum fluorides (e.g. Na₃AlFô), neodymium fluoride (NdF₃), samarium fluoride (SmFs), barium fluoride (BaFz), calcium fluoride (CaF2), lithium fluoride (LiF), and métal oxides such as Silicon oxide (SiO), silicium dioxide (S1O2), titanium oxide (T1O2), aluminum oxide (AI2O3), more preferably selected from the group consistîng of magnésium fluoride (MgFj and Silicon dioxide (SiOz) and still more preferably magnésium fluoride (MgF₂). Preferably, the absorber layers are independently made from one or more selected from the group consistîng of aluminum (Al), silver (Ag), copper (Cu), palladium (Pd), platinum (Pt), titanium (Ti), vanadium (V), iron (Fe) S tin (Su), tungsten (W), molybdenum (Mo), rhodium (Rh), Niobium (Nb), chromium (Cr), nickel (Ni), métal oxides thereof, métal sulfides thereof, métal carbides thereof, and métal alloys thereof, more preferably selected from the group consistîng of chromium (Cr), nickel (Ni), métal oxides thereof, and métal alloys thereof, and still more preferably selected from the group consistîng of chromium (Cr), nickel (Ni), and métal alloys thereof. Preferably, the magnetic layer 10 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 interférence pigment particles comprising a sevenlayer Fabry-Perot structure are preferred, it is particularly preferred that the magnetic thin film interférence pigment particles comprise a seven-layer Fabry-Perot absorber/dielectric/reflector/magnetic/reflector/dielectric/absorber multilayer structure consistîng of a Cr/MgF₂/Al/Ni/Al/MgF₂/Cr multilayer structure.

The magnetic thin film interférence 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 20 multilayer structures and seven-layer Fabry-Perot multilayer 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. Typîcal examples of multilayer pigment particles being considered as safe for human health and the environment can 25 be found in EP 2 402 401 B1 whose content is hereby incorporated by reference in its entirety.

Magnetic thin film interférence pigment particles described herein are typically manufactured by a conventional déposition technique of the different required layers onto a web. After déposition ofthe desired number of layers, e.g. by physical vapor déposition (PVD), Chemical vapor déposition (CVD) or electrolytic déposition, the stack of layers is removed from the web, either 30 by dissolving a release layer in a suitable solvent, or by stripping the material from the web. The so-obtained material is then broken down to flakes which hâve to be further processed by grinding, milling (such as for example jet milling processes) or any suitable method so as to obtain pigment particles of the required size. The resulting product consiste of fiat flakes with broken edges, irregular shapes and different aspect ratios. Further information on the préparation 35 of suitable magnetic thin film interférence pigment particles can be found e.g. in EP 1 710 756

Al and ΕΡΊ 666 546 Al whose contents are hereby incorporated by reference.

Suitable magnetic cholesteric liquid crystal pigment particles exhibîting optically variable characteristics include without limitation magnetic monolayered cholesteric liquid crystal pigment particles and magnetic multiiayered cholesteric liquid crystal pigment particles. Such pigment particles are disclosed for example în WO 2006/063926 Al, US 6,582,781 and US 6,531,221. WO 2006/063926 Al discloses monolayers and pigment particles obtained therefrom with high brilliance and colorshifting 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 nanoparti cl es. US 6,582,781 and US 6,410,130 disclose plateletshaped cholesteric multilayer pigment particles which comprise the sequence A*/B/A², wherein A¹ and A² may be identîcal or different and each comprises at least one cholesteric layer, and B is an interlayer absorbing ail 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.

Suitable interférence coated pigments 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 hâve magnetic properties. For example, suitable interférence coated pigments 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 métal oxides, or they hâve a structure consisting of a core made of synthetic or natural micas, layered silicates (e.g. talc, kaolin and sericîte), glasses (e.g. borosilicates), Silicon dioxîdes (SiO₂), aluminum oxides (AbCh), titanium oxides (TiO₂), graphites and mixtures of two or more thereof. Furthermore, one or more additional layers such as coloring layers may be present.

The magnetic or magnetizable pigment particles described herein may be surface treated so as to protect them against any détérioration 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.

The method described herein further comprises the step ii) of exposing the coating layer (x10) to the magnetic field of the magnetic assembly (xOO) described herein so as to biaxially orient at least a part ofthe platelet-shaped magnetic or magnétisable pigment particles to hâve both their X-axis and Y-axis substantially paraliel to the substrate (x20) surface and a step iii) of at least partially curing the radiation curable coating composition of step ii) to a second State so as to fix the platelet-shaped magnetic or magnetizable pigment particles in their adopted positions and orientations. As used herein, by “at least partially curing the radiation curable coating composition”, it means that the plateletshaped magnetic or magnetizable pigment particles are fixed/ffozen in their adopted positions and orientations and cannot move and rotate anymore (also referred in the art as “pinning” of the particles).

The distance (h) (shown for example in Fig. 2), from the uppermost surface of the bar dipole magnets (x31) of the sets (SI, S2, S3, etc.) of the magnetic assembly (xOO) described herein and the lowermost surface of the substrate (x20) facing said magnetic assembly is preferably smaller than about 20 mm and greater than or equal to about 2 mm, more preferably smaller than or equal to about 10 mm and greater than or equal to about 4 mm and still more preferably smaller than or equal to about 7 mm and greater than or equal to about 2 mm.

According to one embodiment, the method described herein comprises the step ii) of exposing the coating layer (xlO) to the magnetic field of the magnetic assembly (xOO) consists of a single step using the magnetic assembly (xOO) described herein. The method described herein comprises the step iii) of at least partially curing the radiation curable coating composition of step ii) to allow the platelet-shaped magnetic or magnetizable pigment particles to be fixed in their adopted positions and orientations, wherein said at least partially curing step may be carried out partially sîmultaneously with or subsequently to step ii). During the method described herein, the magnetic assembly (xOO) described herein is preferably a static device. The magnetic assembly (xOO) described herein is mounted in the vicinity of the transferring device described herein, wherein said transferring device is preferably a belt comprising grippers or one or more rotating cylinders.

According to one embodiment shown for example in Fig. 5A-5C, the method described herein comprises the step ii) of exposing the coating layer (xlO) to the magnetic field of the magnetic assembly (xOO) and a further step of subsequently exposing the coating layer (xlO) to the magnetic field of a magnetic-field-generating device comprising one or more hard magnetic magnets (Ml), said one or more hard magnetic magnets (Ml) being preferably mounted on a rotating magnetic cylinder (x60), so as to mono-axially re-orient at least a part of the platelet-shaped magnetic or magnétisable particles, said further step being carried out subsequently to step ii). The method described herein comprises the step iii) of at least partially curing the radiation curable coating composition of step ii), wherein said step may be carried out partially simultaneously with or subsequently to the step of mono-axially re-orienting the platelet-shaped magnetic or magnétisable particles, preferably partially simultaneously with said step of re-orienting. WO 2015/0S6257 Al discloses processes wherein a subséquent step of mono-axially re-orienting the plateletshaped magnetic or magnétisable particles is also carried oui. During the method described herein, the magnetic assembly (xOO) described herein is preferably a static device. Fig. 5A-C iliustrate said method, wherein the one or more magnets (Ml ) of the magnetic-field-generating device are mounted on the rotating magnetic cylinder described herein (560) and the substrate (520) carrying the coating layer (510, not shown in Fig. 5A) concomîtantly moves with said rotating magnetic cylinder (560). According to one embodiment shown în Fig. 5A, the magnetic assembly (500) described herein is mounted in the vicinity of the transferring device described herein, wherein said transferring device is preferably a belt comprising grippers. According to another embodiment shown in Fig. 5B-C, the magnetic assembly (500) described herein is mounted in the vicinity of the transferring device described herein, wherein said transferring device preferably consists of one or more cylinders (570-a and 570-b). The method described in Fig. 5A may be carried out with the substrate (520) facing the magnetic assembly (500); however, the same method may be carried out with the coating layer (510 not shown in Fig. 5A) facîng the magnetic assembly (500).

According to one embodiment shown for example in Fig. 5D, the method described herein comprises a step ii) of exposing, in a single step, the coating layer (xlO) to the interaction of magnetic fields of the magnetic assembly (xOO) described herein and of a magnetic-field-generating device comprising one or more hard magnetic magnets (Μ 1 ), the one or more hard magnetic magnets (Ml) being preferably mounted on a rotating magnetic cylinder (x60) also acting as transferring device. The method described herein comprises the step iii) of at least partially curing the radiation curable coating composition of step ii), wherein said step may be carried out partially simultaneously with or subsequently to step ii). During the method described herein, the magnetic assembly (xOO) described herein is preferably a static device and the one or more hard magnetic magnets (Ml) concomîtantly move with the substrate (x20) carrying the coating layer (xlO). Fig. 5D illustrâtes said method, wherein tire magnets (Ml) of the magneticfield-generating device are mounted on the rotating magnetic cylinder described herein (560) and the substrate (520) carrying the coating layer (510) concomîtantly moves with said rotating magnetic cylinder (560) in the vicinity of the static magnetic assembly (500) described herein. According to said embodiment, the magnetic assembly (500) described herein is mounted in the vicinity of the rotating magnetic cylinder described herein (560). . Figures 4 of WO 2019/141452 Al and WO 2019/141/453 Al disclose processes wherein hard magnetic magnets (x30 in said PCT applications) are simultaneously used with a magnetic-field-generating device (x40 in said PCT applications). According to one embodiment shown for example in Fig 5E, the method described herein comprises a step ii) of exposing the coating layer (xlO) to the magnetic field of a tirs magnetic assembly (xOOa) described herein, an optional further step of selectively at least partially curing (depicted with a sélective curing unit (x80)) one or more first areas of the coating layer (xlO) of the radiation curable coating composition of step ii) so as to fix at least apart of the non-spherical magnetic or magnetizable particles in their adopted positions and orientations such that one or more second areas of the coating layer (xl 0) are not exposed to irradiation; and further subsequently, a step of exposing, in a single step, the coating layer (xlO) to the interaction of magnetic fields of a second magnetic assembly (xOOb) described herein and of a magnetic-fïeld-generating device comprising one or more hard magnetic magnets (Ml), the one or more hard magnetic magnets (Ml) being preferably mounted on a rotating magnetic cylinder (x60) also acting as transferring device. The method described herein comprises the step iii) of at least partially curing the radiation curable coating composition of step ii), wherein said step may be carried out partially simultaneously with or subsequently to step ii). During the method described herein, the magnetic assemblies (xOOa and xOOb) described herein are preferably static devices and the one or more hard magnetic magnets (Ml) concomitantly move with the substrate (x20) carrying the coating layer (xlO). The method described in Fig. 5E may be carried out with the substrate (520) facîng the magnetic assembly (500); however, the same method may be carried out with the coating layer (510 not shown in Fig. 5E) facing the magnetic assembly (500).

According to one embodiment shown for example in Fig. 5D, the method described herein comprises a step ii) of exposing, in a single step, the coating layer (xlO) to the interaction of magnetic fields of the magnetic assembly (xOO) described herein and of one or more soft magnetic plates (Ml) carrying one or more indicia in the form of voids and/or indentations and/or protrusions, said soft magnetic plates being preferably mounted on a rotating magnetic cylinder or being placed on a moveable device below the substrate (x20). The method described herein comprises the step iii) of at least partially curing the radiation curable coating composition of step ü) to allow the platelet-shaped magnetic or magnetizable pigment particles to be fixed in their adopted positions and orientations, wherein said at least partially curing step may be carried out partially simultaneously with or subsequently to step ii). During the method described herein, the magnetic assembly (xOO) described herein is preferably a static device and the one or more soft magnetic plates (Ml) concomitantly move with the substrate (x20) carrying the coating layer (xlO). Suitable soft magnetic plates carrying one or more indicia in the form of voids and/or indentations and/or protrusions are either made of one or more metals, alloys or compounds of high magnetic permeability or are made of a composite comprising from about 25 wt-% to about 95 wt-% of soft magnetic particles dispersed in a non-magnetic materiai, the weight percents being based on the total weight of the soft magneticplate and are disclosed in WO 2018/033512 Al and WO 2018/019594 Al. Figure 3 of WO 201 8/033512 Al disclose a process wherein a soft magnetic plate (xlÛ in said PCT application) is also used in addition to a magnetic-field-generating device (x40 in said PCT application). Fig. 4 of WO 2018/019594 Al disclose a process wherein a soft magnetic plate (x50 in said PCT application) is also used in addition to a magnetic-fieldgeneratîng device (x60 in said PCT application). According to said embodiment, the magnetic assembly (xOO) described herein is mounted in the vicînity of the transferring device described herein, wherein said transferring device being preferably one or more rotating cylinders. According to one embodiment shown for example in Fig, 5E, the method described herein comprises a step ii) of exposîng the coating layer (xlO) to the magnetic field of a first magnetic assembly (xOOa) described herein, an optîonal further step of selectively at least partially curing (depicted with a sélective curing unit (x80)) one or more first areas of the coating layer (xl 0) of the radiation curable coating composition of step ii) so as to fix at least a part of the non-spherical magnetic or magnetizabie particles in their adopted positions and orientations such that one or more second areas of the coating layer (xl 0) are not exposed to irradiation; and further subsequently, a step of exposîng, in a single step, the coating layer (xlO) to the interaction of magnetic fields of a second magnetic assembly (xOOb) described herein and of one or more soft magnetic plates (MI) carrying one or more indicia in the form of voids and/or indentations and/or protrusions, said soft magnetic plates being preferably mounted on a rotating magnetic cylinder or being placed on a moveable device below the substrate (x20). The method described herein comprises the step iii) of at least partially curing the radiation curable coating composition of step îi) to allow the platelet-shaped magnetic or magnetizabie pigment particles to be fixed in their adopted positions and orientations, wherein said at least partially curing step may be carried out partially simultaneously with or subsequently to step ii). During the method described herein, the magnetic assemblies (xOO and xOOb) described herein are preferably static devices and the one or more hard soft magnetic plates (Ml) concomitant!y move with the substrate (x20) carrying the coating layer (xl 0). The method described in Fig. 5E may be carried out with the substrate (520) facing the magnetic assembly (500); however, the same method may be carried out with the coating layer (510 not shown in Fig. 5E) facing the magnetic assembly (500).

According to one embodiment shown for example in Fig. 5A-C, the method described herein comprises the step ii) of exposing the coating layer (xlO) to the magnetic field of the magnetic assembly (xOO); and, subsequently to this step ii), a further step of selectively at least partially curing (depicted with a sélective curing unit (580)) one or more first areas of the coating layer (xlO) of the radiation curable coating composition of step ii) so as to fix at least a part ofthe non-sphencal magnetic or magnetizable particles in their adopted positions and orientations such that one or more second areas ofthe coating layer (xlO) are not exposed to irradiation; and further subsequently, a step of exposing the coating layer (xlO) to the magnetic field of a magnetic-field-generating device comprising one or more hard magnetic magnets (Ml), the one or more hard magnetic magnets (Ml) being preferably mounted on a rotating magnetic cylinder (x60) also acting as transferring device, so as to mono-axially re-orient at least a part of the platelet-shaped magnetic or magnétisable particles in the one or more second areas. The method described herein comprises the step iiî) of at least partially curing the radiation curable coating composition of step ii), wherein said step may be carried out partially simultaneously with or subsequently to the step of re-orientîng the platelet-shaped magnetic or magnétisable particles, preferably partially simultaneously with said step of re-orienting. During the method described herein, the magnetic assembly (xOO) described herein is preferably a static device and the one or more hard magnetic magnets (MI) concomitantly move with the substrate (x20) carrying the coating layer (xlO). Fig. 5A-C illustrate said method, wherein the one or more magnets (Ml) of the magnetic-fieldgenerating device are mounted on the rotating magnetic cylinder described herein (560) and the substrate (520) carrying the coating layer (510, not shown in Fig. 5A) concomitantly moves with said rotating magnetic cylinder (560) in the vicinity of the static magnetic assembly (500) described herein. According to one embodiment shown in Fig. 5A, the magnetic assembly (500) described herein is mounted in the vicinity of the transferring device described herein, wherein said transferring device is preferably a belt comprising grippers. According to another embodiment shown in Fig. 5B-C, the magnetic assembly (500) described herein is mounted in the vicinity of the transferring device described herein, wherein said transferring device preferably being one or more

3S cylinders (570a and 570-b).

According to one embodiment, the method described herein comprises the step ii) of exposing the coating layer (xlO) to the magnetic field ofthe magnetic assembly (xOO) and a further step of subsequently exposing the coating layer (xl 0) to the magnetic field of a first magnetic-field-generating device comprising one or more hard magnetic magnets (Mla), said one or more hard magnetic magnets (M l a) being preferably mounted on a rotating magnetic cylinder (x60a) also acting as transferring device, so as to mono-axially re-orient at least a part of the platelet-shaped magnetic or magnétisable particles, said further step being carried out subsequently to step ii); a further step of selectively at least partially curing (depicted with a sélective curing unit (x80)) one or more first areas of the coating layer (xlO) of the radiation curable coating composition of step ii) so as to fix at least a part of the non-spherical magnetic or magnetizable particles in their adopted positions and orientations such that one or more second areas ofthe coating layer (xlO) are not exposed to irradiation; and further subsequently, a step of exposing the coating layer (xlO) to the magnetic field of a second magnetic-field-generating device comprising one or more hard magnetic magnets (Mlb), said one or more hard magnetic magnets (Mlb) being preferably mounted on a rotating magnetic cylinder (x60b) also acting as transferring device, Partially simultaneously with or subsequently to the step of orienting the coating layer (xlO) to the magnetic field ofthe second magnetic-field-generating device comprising one or more hard magnetic magnets (Ml), the method described herein comprises the step of at least partially curing the radiation curable coating composition.

According to one embodiment, the method described herein comprises the step ii) of exposing the coating layer (xl 0) to the magnetic field of a first magnetic assembly (xOOa) and a further step of subsequently exposing the coating layer (xlO) to the magnetic field of a first magnetic-field-generating device comprising one or more hard magnetic magnets (Ml), said one or more hard magnetic magnets (Ml a) being preferably mounted on a rotating magnetic cylinder (x60a) also acting as transferring device, so as to monoaxially re-orient at least a part of the platelet-shaped magnetic or magnétisable particles, said further step being carried out subsequently to step ii); a further step of selectively at least partially curing (depicted with a sélective curing unit (x80)) one or more first areas of the coating layer (xlO) of the radiation curable coating composition of step ii) so as to fix at least a part of the non-spherical magnetic or magnetizable particles in their adopted positions and orientations such that one or more second areas of the coating layer (xl 0) are not exposed to irradiation; further subsequently, a step of exposing the coating layer (xlO) to the magnetic field of a second magnetic assembly (xOOb); further subsequently, a step of exposîng the coating layer (xl 0) to the magnetic field of a second magnetic-fieldgenerating device comprising one or more hard magnetic magnets (Ml b), said one or more hard magnetic magnets (Mlb) being preferably mounted on a rotating magnetic cylinder (x60b) also acting as transferring device. Partially simultaneously with or subsequently to the step of orienting the coating layer (xlO) to the magnetic field of the second magnetic-field-generating device comprising one or more hard magnetic magnets (Mlb), the method described herein comprises the step of at least partially curing the radiation curable coating composition.

According to one embodiment, the method described herein comprises the step ii) of exposing the coating layer (xlO) to themagnetic field of a first magnetic assembly (xOOa) such as those described herein; and, subsequently to this step ii), a further step of selectîvely at least partially curing one or more first areas of the coating layer (xlO) of the radiation curable coating composition of step ii) so as to fix at least a part of the nonspherical magnetic or magnetizable particles in their adopted positions and orientations such that one or more second areas of the coating layer (xlO) are not exposed to irradiation; and further subsequently, a single step of exposing the coating layer (xlO) to the interaction of the magnetic fields of a second magnetic assembly (xOOb) such as those described herein and of a magnetic-field-generating device comprising one or more hard magnetic magnets (Ml), the one or more hard magnetic magnets (Ml) being preferably mounted on a rotating magnetic cylinder (x60). Partially simultaneously with or subsequently to the step of orienting the coating layer (xl 0) to the interaction of the magnetic fields of the second magnetic assembly (xOOb) and of the magnetic-fieldgenerating device, the method described herein comprises the step of at least partially curing the radiation curable coating composition. During the method described herein, the magnetic assemblies (xOO) described herein are preferably static devices and the magnetic-field-generating devices comprising the one or more hard magnetic magnets (Ml) concomitantly move with the substrate (x20) carrying the coating layer (xlO) and the substrate (x20) carrying the coating layer (xl 0) concomitantly moves with said rotating magnetic cylinders in the vîcinîty of the static magnetic assemblies (xOO) described herein.

According to one embodiment, the method described herein comprises the step ü) of exposing the coating layer (x 10) to the magnetic field of a first magnetic assembly (xOOa) such as those described herein; and, subsequently to this step ii), a further step of selectîvely at least partially curing one or more first areas of the coating layer (xlO) of the radiation curable coating composition of step ii) so as to fix at least a part of the nonspherical magnetic or magnetizable particles in their adopted positions and orientations such that one or more second areas ofthe coating layer (xlO) are not exposed to irradiation; and further subsequently, a single step of exposing the coating layer (xl 0) to the interaction of the magnetic fields of a second magnetic assembly (xOOb) such as those described herein and of one or more soft magnetic plates such as those described herein. Partially simultaneously with or subsequently to the step of orienting the coating layer (xlO) to the interaction of the magnetic fields of the magnetic assembly (xOOb) and the soft magnetic plate, the method described herein comprises the step of at least partially curing the radiation curable coating composition.

According to one embodiment shown for example in Fig. 5F, the method described herein comprises the step ii) of exposing, in a single step, the coating layer (xlO) to the interaction of magnetic fields of a first magnetic assembly (xOOa) such as those described herein and of a first magnetic-field-generating device comprising one or more hard magnetic magnets (Mla), the one or more hard magnetic magnets (Ml a) being preferably mounted on a rotating magnetic cylinder (x60a) also acting as a transferring device; a further step of selectîvely at least partially curing one or more first areas of the coating layer (xlO) of the radiation curable coating composition of step ii) so as to fix at least a part of the non-spherical magnetic or magnetizable particles in their adopted positions and orientations such that one or more second areas of the coating layer (xlO) are not exposed to irradiation; further subsequently, a step of exposing the coating layer (xlO) to the magnetic field of a second magnetic assembly (xOOb); further subsequently, exposing the coating layer (xlO) to the magnetic field of a second magnetic-field-generating device comprising one or more hard magnetic magnets (Mlb), said one or more hard magnetic magnets (Mlb) being preferably mounted on a rotating magnetic cylinder (x60b) also acting as transferring device. Partially simultaneously with or subsequently to the step of orienting the coating layer (xl0) to the magnetic field of the second magnetic-fieldgenerating device comprising the one or more hard magnetic magnets (Mlb), the method described herein comprises the step of at least partially curing the radiation curable coating composition.

According to one embodiment shown for example in Fig. 5F, the method described herein comprises the step ii) of exposing, in a single step, the coating layer (xlO) to the interaction of magnetic fields of a first magnetic assembly (xOOa) such as those described herein and of one or more soft magnetic plates (Mla) such as those described herein; a further step of selectîvely at least partially curing one or more first areas of the coating layer (xl 0) of the radiation curable coating composition of step ii) so as to fix at least a part of the non-spherical magnetic or magnetîzable particles in their adopted positions and orientations such that one or more second areas of the coating layer (xlO) are not exposed to irradiation; further subsequently, a step of exposing the coating layer (xlO) to the magnetic field of a second magnetic assembly (xOOb); further subsequently, a step of exposing the coating layer (xlO) to the magnetic field of a magnetic-field-generating device comprising one or more hard magnetic magnets (Mlb), said one or more hard magnetic magnets (Mlb) being preferably mounted on a rotating magnetic cylinder (x60) also acting as transferring device. Partially simultaneously with or subsequently to the step of orienting the coating layer (xl 0) to the magnetic field of the magnetic-fieldgenerating device comprising the one or more hard magnetic magnets (Mlb), the method described herein comprises the step of at least partially curing the radiation curable coating composition.

According to one embodiment shown for example in Fig. 5G, the method described herein comprises the step ii) of exposing, in a single step, the coating layer (xlO) to the interaction of magnetic fields of a first magnetic assembly (xOOa) such as those described herein and a first magnetic-field-generating device comprising one or more hard magnetic magnets (Mla), the one or more hard magnetic magnets (Mla) being preferably mounted on a rotating magnetic cylinder (x60a) also acting as a transferring device; a further step of selectively at least partially curing one or more first areas ofthe coating layer (xlO) of the radiation curable coating composition of step ii) so as to fix at least a part of the nonspherical magnetic or magnetîzable particles in their adopted positions and orientations such that one or more second areas ofthe coating layer (xlO) are not exposed to irradiation; further subsequently, a step of exposing the coating layer (xlO) to the magnetic field of a second magnetic assembly (xOOb); and further subsequently exposing, in a single step, the coating layer (xl 0) to the interaction of magnetic fields of a third magnetic assembly (xOOc) such as those described herein and of a second magnetic-field-generating device comprising one or more hard magnetic magnets (Mlb), the one or more hard magnetic magnets (Mlb) being preferably mounted on a rotating magnetic cylinder (x60b) also acting as a transferring device. Partially simultaneously with or subsequently to the step of orienting the coating layer (xlO) to the interaction of the magnetic fields of the second magnetic assembly (xOOb) and of the second magnetic-field-generating device, the method described herein comprises the step of at least partially curing the radiation curable coating composition.

According to one embodiment shown for example in Fig. 5G, the method described herein comprises tho.step ii) of exposîng, in a single step, the coating layer (xlO) to the interaction of magnetic fields of a first magnetic assembly (xOOa) such as those described herein and a first magnetic-field-generating device comprising one or more hard magnetic magnets (Ml a), the one or more hard magnetic magnets (Ml a) being preferably mounted on a rotating magnetic cylinder (x60a) also acting as a transferring device; a further step of selectively at least partially curing one or more first areas of the coating layer (xlO) of the radiation curable coating composition of step ii) so as to fix at least a part of the nonspherical magnetic or magnetizabie particles in their adopted positions and orientations such that one or more second areas ofthe coating layer (xlO) are not exposed to irradiation; further subsequently, a step of exposîng the coating layer (xlO) to the magnetic field of a second magnetic assembly (xOOb); and further subsequently exposîng, in a single step, the coating layer (xlO) to the interaction of magnetic fields of a third magnetic assembly (xOOc) such as those described herein and of one or more soft magnetic plates (Mlb) such as those described herein. Partially simultaneously with or subsequently to the step of orienting the coating layer (xlO) to the interaction of the magnetic fields ofthe third magnetic assembly (xOOc) and of the one or more soft magnetic plates, the method described herein comprises the step of at least partially curing the radiation curable coating composition.

According to one embodiment shown for example in Fig. 5 G, the method described herein comprises the step îî) of exposîng, in a single step, the coating layer (xlO) to the interaction of magnetic fields of a first magnetic assembly (xOOa) such as those described herein and of one or more soft magnetic plates (Μ 1 a) such as those described herein; a further step of selectively ai least partially curing one or more first areas of the coating layer (xl 0) of the radiation curable coating composition of step fi) so as to fix at least a part of the non-spherical magnetic or magnetizabie particles in their adopted positions and orientations such that one or more second areas of the coating layer (xlO) are not exposed to irradiation; further subsequently, a step of exposîng the coating layer (xl 0) to the magnetic field of a second magnetic assembly (xOOb); and further subsequently exposîng, in a single step, the coating layer (xlO) to the interaction of magnetic fields of a third magnetic assembly (xOOc) such as those described herein and of a magnetic-fieldgenerating device comprising one or more hard magnetic magnets (Mlb), the one or more hard magnetic magnets (Mlb) being preferably mounted on a rotating magnetic cylinder (x60) also acting as a transferring device. Partially simultaneously with or subsequently to the step of orienting the coating layer (xlO) to the interaction ofthe magnetic fields of the third magnetic assembly (xOOc) and of the second magnetic-field generating device, the method described herein comprises the step of at least partially curing the radiation curable coating composition.

According to one embodiment shown for example in Fig. 5 G, the method described herein comprises the step ii) of exposing, in a single step, the coating layer (xlO) to the interaction of magnetic fields of a first magnetic assembly (xOOa) such as those described herein and of one or more first soft magnetic plates (Ml a) such as those described herein; a further step of selectively at least partially curing one or more first areas of the coating layer (xl 0) ofthe radiation curable coating composition of step ii) so as to fix at least a part of the non-spherical magnetic or magnetizable particles in their adopted positions and orientations such that one or more second areas ofthe coating layer (xlO) are not exposed to irradiation; further subsequently, a step of exposing the coating layer (xlO) to the magnetic field of a second magnetic assembly (xOOb); and further subsequently exposing, in a single step, the coating layer (xl0) to the interaction of magnetic fields of a third magnetic assembly (xOOc) such as those described herein and of one or more second soft magnetic plates (Mlb) such as those described herein. Partially simultaneously with or subsequently to the step of orienting the coating layer (xl 0) to the interaction of the magnetic fields of the third magnetic assembly (xOOc) and of the second soft magnetic plate, the method described herein comprises the step of at least partially curing the radiation curable coating composition.

According to one embodiment shown for example in Fig. 5H, the method described herein comprises the step ii) of a) exposing the radiation curable coating composition to the interaction of the magnetic fields of a first magnetic assembly (xOOa) described herein; then b) exposing, in a single step, the coating layer (xlO) to the interaction of magnetic fields of a second magnetic assembly (xOOb) such as those described herein and a first magnetic-field-generating device comprising one or more hard magnetic magnets (Mla), the one or more hard magnetic magnets (Mla) being preferably mounted on a rotating magnetic cylinder (x60a) also acting as a transferring device; a further step of selectively at least partially curing one or more first areas ofthe coating layer (xlO) ofthe radiation curable coating composition of step ii) so as to fix at least a part of the nonspherical magnetic or magnetizable particles in their adopted positions and orientations such that one or more second areas of the coating layer (xlO) are not exposed to irradiation; further subsequently, a step of exposing the coating layer (xlO) to the magnetic field of a third magnetic assembly (xOOc); and further subsequently exposing, in a single step, the coating layer (xlO) to the interaction of magnetic fields of a fourth magnetic assembly (xOOd) such as those described herein and of a second magnetic-field-generating device comprising one or more hard magnetic magnets (Mlb), the one or more hard magnetic magnets (Mlb) being preferably mounted on a rotating magnetic cylinder (x60b) also acting as a transferring device. Partially simultaneously with or subsequently to the step of orienting the coating layer (xlO) to the interaction of the magnetic fields of the fourth magnetic assembly (xOOc) and of the second magnetic-field-generating device, the method described herein comprises the step of at least partially curing the radiation curable coating composition. The method described in Fig. 5H may be carried out with the substrate (520) facing the magnetic assembly (500); however, the same method may be carried out with the coating layer (510 not shown in Fig. 5H) facing the magnetic assembly (500).

According to one embodiment shown for example in Fig. 5H, the method described herein comprises the step ii) of a) exposing the radiation curable coating composition to the interaction of the magnetic fields of a first magnetic assembly (xOOa) described herein; then b) exposing, in a single step, the coating layer (xlO) to the interaction of magnetic fields of a second magnetic assembly (xOOb) such as those described herein and a first magnetic-field-generating device comprising one or more hard magnetic magnets (Mla), the one or more hard magnetic magnets (Mla) being preferably mounted on a rotating magnetic cylinder (x60) also acting as a transferring device; a further step of selectively at least partially curing one or more first areas of the coating layer (xl 0) of the radiation curable coating composition of step ii) so as to fix at least a part of the nonspherical magnetic or magnetizable particles în their adopted positions and orientations such that one or more second areas of the coating layer (x 10) are not exposed to irradiation; further subsequently, a step of exposing the coating layer (xl 0) to the magnetic field of a third magnetic assembly (xOOc); and further subsequently exposing, in a single step, the coating layer (x 10) to the interaction of magnetic fields of a fourth magnetic assembly (xOOd) such as those described herein and of one or more soft magnetic plates (Mlb) such as those described herein. Partially simultaneously with or subsequently to the step of orienting the coating layer (xl0) to the interaction of the magnetic fields of the fourth magnetic assembly (xOOd) and of the one or more soft magnetic plates (Mlb), the method described herein comprises the step of at least partially curing the radiation curable coating composition. This embodiment îs shown in Fig 5H, wherein the magnets (Mlb) of the second magnetic-field-generating device are replaced by the soft magnetic plates. The method described in Fig. 5H may be carried out with the substrate (520) facing the magnetic assembly (500); however, the same method may be carried out with the coating layer (510 not shown in Fig. 5H) facing the magnetic assembly (500).

According to one embodiment shown for example in Fig. 5H, the method described herein comprises the step ii) of a) exposing the radiation curable coating composition to the interaction of the magnetic fields of a first magnetic assembly (xOOa) described herein; then b) exposing, in a single step, the coating layer (xlO) to the interaction of magnetic fields of a second magnetic assembly (xOOb) such as those described herein and of one or more soft magnetic plates (Ml a) such as those described herein; a further step of selectively at least partially curing one or more first areas of the coating layer (xl 0) of the radiation curable coating composition of step ii) so as to fix at least a part of the nonspherical magnetic or magnétisable particles in their adopted positions and orientations such that one or more second areas of the coating layer (xlO) are not exposed to irradiation; further subsequently, a step of exposing the coating layer (xlO) to the magnetic field of a third magnetic assembly (xOOc); and further subsequently exposing, in a single step, the coating layer (xlO) to the interaction of magnetic fields of a fourth magnetic assembly (xOO) such as those described herein and of a magnetic-field-generating device comprising one or more hard magnetic magnets (Ml), the one or more hard magnetic magnets (Ml) being preferably mounted on a rotating magnetic cylinder (x60) also acting as a transferring device. Partially simultaneously with or subsequently to the step of orienting the coating layer (xl 0) to the interaction of the magnetic fields of the fourth magnetic assembly (xOOd) and of the second magnetic-field-generating device, the method described herein comprises the step of at least partially curing the radiation curable coating composition. The method described in Fig. 5H may be carried out with the substrate (520) facing the magnetic assembly (500); however, the same method may be carried out with the coating layer (510 not shown in Fig. 5H) facing the magnetic assembly (500).

According to one embodiment shown for example in Fig. 5H, the method described herein comprises the step ii) of a) exposing the radiation curable coating composition to the interaction of the magnetic fields of a first magnetic assembly (xOOa) described herein; then b) exposing, in a single step, the coating layer (xlO) to the interaction of magnetic fields of a second magnetic assembly (xOOb) such as those described herein and of one or more first soft magnetic plates (Mla) such as those described herein; a further step of selectively at least partially curing one or more first areas of the coating layer (xl 0) of the radiation curable coating composition of step ii) so as to fix at least a part of the non-spherical magnetic or magnetizable particles in their adopted positions and orientations such tirât one or more second areas of the coating layer (xl 0) are not exposed to irradiation; further subsequently, a step of exposing the coating layer (xlO) to the magnetic field of a . ._s third magnetic assembly (xOOc); and further subsequently exposing, in a single step, the coating layer (xlO) to the interaction of magnetic fields of a fourth magnetic assembly (xOOd) such as those described herein and of one or more second soft magnetic plates (Mlb) such as those described herein. Partially simultaneously with or subsequently to the step of orienting the coating layer (xlO) to the interaction of the magnetic fields of the fourth magnetic assembly (xOOd) and of the one or more second soft magnetic plates (Mlb), the method described herein comprises the step of at least partially curing the radiation curable coating composition. This embodiment is shown in Fig 5G, wherein the magnets (Mla) of the first magnetic-field-generating device and the magnets (Mlb) of the second magnetic-field-generating device are replaced by the soft magnetic plates. The method described in Fig. 5H may be carried out with the substrate (520) facing the magnetic assembly (500); however, the same method may be carried out with the coating layer (510 not shown in Fig. 5H) facing the magnetic assembly (500).

The one or more hard magnetic magnets (Ml, Ml a, Mlb) described herein are not limited and include for example dipole magnets, quadrupolar magnets and combinations thereof. The foilowing hard magnetic magnets are provided herein as illustrative examples.

Optical effects known as flip-flop effects (also referred in the art as switching effect) include a first printed portion and a second printed portion separated by a transition, wherein pigment particîes are afigned parallel to a first plane in the first portion and pigment particîes in the second portion are aligned parallel to a second plane. Methods and magnets for producing said effects are disclosed for example in in US 2005/0106367 and EP 1 819 525 Bl.

Optical effects known as rolling-bar effects as disclosed in US 2005/0106367 may also be produced. A “rolling bar” effect is based on pigment particîes orientation imitatîng a curved surface across the coating. The observer sees a spéculât reflection zone which moves away or towards the observer as the image is tîlted. The pigment particîes are aligned in a curving fashîon, either foilowing a convex curvature (also referred in the art as négative curved orientation) or a concave curvature (also referred in the art as positive curved orientation). Methods and magnets for producing said effects are disclosed for example în EP 2 263 806 Al, EP 1 674 282 B1,EP2 263 807 Al, WO 2004/007095 A2, WO 2012/104098 Al, and WO 2014/198905 A2.

Optical effects known as Venetîan-blind effects may also be produced. Venetian-blind effects include pigment particîes being oriented such that, along a spécifie direction of observation, they give visibility to an underlying substrate surface, such that îndîcia or other features present on or in the substrate surface become apparent to the observer while they impede the visibility along > another direction of observation Methods and magnets for producing said effects are disclosed for example in US 8,025,952 and EP 1 819 525 Bl.

Optical effects known as moving-ring effects may also be produced. Moving-ring effects consists of optically îllusive images of objects such as funnels, cônes, bowls, circles, ellipses, and hemispheres that appear to move in any x-y direction depending upon the angle of tilt of said optical effect layer. Methods and magnets for producing said effects are disclosed for example in EP 1 710 756 Al, US 8,343,615, EP 2 306 222 Al, EP 2 325 677 A2, WO 2011/092502 A2,US 2013/084411, WO 2014 108404 A2 and WO2014/108303 Al.

Optical effects providing an optical impression of a pattern of moving bright and dark areas upon tîlting said effect may also be produced. Methods and magnets for producing said effects are disclosed for example in WO 2013/167425 Al.

Optical effects providing an optical impression of a loop-shaped body having a size that varies upon tilting said effect may also be produced. Methods and magnets for producing these optical effects are disclosed for example in WO 2017/064052 Al, WO 2017/080698 Al and WO 2017/148789 Al.

Optical effects providing an optical impression of one or more loop-shaped bodîes having a shape that varies upon tilting the optical effect layer may also be produced. Methods and magnets for producing said effects are disclosed for example in WO 2018/054819 Al.

Optical effects providing an optical impression of a moon crescent moving and rotating upon tilting may also be produced. Methods and magnets for producing said effects are disclosed for example in WO 2019/215148 Al.

Optical effects providing an optical impression of a loop-shaped body having a size and shape that varies upon tilting may be produced. Methods and magnets for producing said effects are disclosed for example in the co-pending PCT patent application WO 2020/052862 Al.

Optical effects providing an optical impression of an ortho-parallactic effect, i.e. in the present case under the form of a bright reflective vertical bar moving in a longitudinal direction when the substrate is tilted about a horizontal/latitudinal axis or moving in a horizontal/latitudinal direction when the substrate is tilted about a longitudinal axis may be produced. Methods and magnets for producing said effects are disclosed for example in the co-pending PCT patent application PCT/EP2020/052265.

Optical effects providing an optical impression of one loop-shaped body surrounded by one or more loop-shaped bodies, wherein said one or more loop-shaped bodîes hâve their shape and/or their brightness varying upon tilting may be produced. Methods and magnets for producing said effects are disclosed for example in the co-pending PCT patent application PCT/EP2020/054042.

Optical effects providing.an optical impression of a plurality of dark spots and a plurality of· bright spots moving and/or appearing and/or disappearing not only in a diagonal direction when the substrate is tilted about a vertical/longitudinal axis but also moving and/or appearing and/or disappearing in a diagonal direction when the substrate is tilted may be produced. Methods and magnets for producing said effects are disclosed for example in the co-pending EP patent applications EP19205715.6 and EP19205716.4.

For embodiments of the method described herein wherein a single step of exposing the coating layer (xlO) to the interaction of the magnetic fields of the magnetic assembly (xOO) described herein and of the magnetic-field-generating device comprising the one or more hard magnetic magnets (Ml) described herein, it is preferred to use non-spinning magnetic-field-generating devices. For embodiments of the method described herein wherein an independent step of exposing the coating layer (xlO) to the magnetic field of the magnetic-field-generating device comprising the one or more hard magnetic magnets (Ml) described herein, non-spinning and spinning magnetic-field-generating devices may be used. Optical effects known as moving-ring effects and obtained with spinning magnetic-field-generating device are disclosed in WO 2014 108404 A2 and WO2014/108303 Al. Optical effects providing an optical impression of at least one circularly moving spot or at least one comet-shaped spot rotating around said center of rotation upon tilting and obtained with spinning magnetic-field-generating device are disclosed for example in WO 2019/038371 Al, WO 2019/063778 Al and WO 2019/038369 Al.

The one or more hard magnetic magnets (Ml) described herein may comprise a magnetic plate carrying one or more reliefs, engravings or cut-outs. WO 2005/002866 Al and WO 2008/046702 Al are examples for such engraved magnetic plates.

The method described herein comprises the step iii) of at least partially curing the radiation curable coating layer (xlO) in a first liquid State to a second State so as to fix/freeze the plateletshaped magnetic or magnetizable pigment particles in their adopted positions and orientations. The at least partial curing step iii) described herein is carried out by using the curing unit (x50) described herein. For embodiments described herein wherein a step of selectîvely at least partially curing one or more first areas of the coating layer (xlO) such that one or more second areas of the coating layer (xlO) are not exposed to irradiation, said step is carried out by using the sélective curing unit (x80) described herein.

The radiation curable coating composition described herein must thus noteworthy hâve a first State, i.e. a liquid or pasty state, wherein the coating composition is not yet cured and wet or soft enough, so that the platelet-shaped magnetic or magnetizable pigment particles dispersed in the composition and in the coating layer are freely movable, rotatable and orientable upon exposure to a magnetic field, and a second cured (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.

Such a firet and second State is preferably provided by using a certain type of coating composition. For example, the components of the radiation curable 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 an exposure to an electromagnetic radiation. That îs, 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 plateletshaped 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, ingrédients 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 fulfill the requirements of the process used to transfer the ink or coating composition to the substrate surface. Consequently, the binder material comprised in the coating composition described herein is typically chosen among those known in the art and dépends on the coating or printing process used to apply the ink or coating composition and tire chosen hardening process. The at least partial curing step iii) include a Chemical reaction of the binder and optionai initiator compounds and/or optionai cross-linking compounds comprised in the radiation curable coating composition. Such a Chemical reaction includes the initiation of a Chemical reaction by a radiation mechanism includîng without limitation Ultraviolet-Visible light radiation curing (hereafter referred as UV-Vis curing) and electronic beam radiation curing (E-beam curing) and may be initiated by heat or IR irradiation.

Radiation curing îs carried out during the method described herein, and UV-Vis light radiation curing is more preferred, since these technologies advantageously lead to very fast curing processes and hence drastically decrease the préparation 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 conséquence, 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 actinie 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 medium50 pressure mercury arc (MPMA) or a metal-vapor arc lamp, as the source, of the actinie radiation. Therefore, suitable radiation curable coating composition for the present invention include radiation curable compositions that may be cured by UV-visible light radiation (hereafter refeired as UV-Vis-curable) or by E-beam radiation (hereafter referred as EB). According to one particularly preferred embodiment of the present invention, the radiation curable coating composition described herein is a UV-Vis-curabie coating composition.

Preferably, the UV-Vis-curable coating composition described herein 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 în tum 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 tum initiate the polymerization so as to harden the coating composition. Depending on the monomers, oligomers or prepolymers used to préparé 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-amînoketones, alphahydroxyketones, phosphine oxides and phosphine oxide dérivatives, as well as mixtures of two or more thereof. Suitable examples of cationic photoinitiators are known to those skilled în the art and include without limitation onium salts such as organic iodonium salts (e.g. diaryl iodoinium salts), oxonium (e.g. tri aryl oxonium 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-thîoxanthone (CTX) and 2,4-diethylthioxanthone (DETX) and mixtures of two or more thereof. The one or more photoinitiators comprised in the UV-Vis-curable coating compositions are preferably present în 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. The radiation curable coating composition described herein may further comprise one or more coloring components selected from the group consisting of organic pigment particles, inorganic pigment particles, and organic dyes, and/or one or more additives. The latter include without limitation compounds and materials that are used for adjusting physical, rheological and chemical parameters of the coating composition such as the viscosity (e.g. solvents, thickeners and surfactants), the consistency (e.g. anti-settling agents, fillers and plasticizers), the foaming properties (e.g. antifoaming agents), the lubricating properties (waxes, oils), UV stability (photo stabilizers), the adhesion properties, the antistatic properties, the storage stability (polymerization inhîbîtors) etc. Additives described herein may be present in the coating composition in amounts and în forms known in the art, including so-called nano-materials where at least one ofthe dimensions of the additive is in the range of l to 1000 nm.

The radiation curable 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 reactîvity and stability (photosensîtizers 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 îs în the range of 1 to 1000 nm.

The radiation curable 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 infraredabsorbing materials. As used herein, the term “machine readable material” refers to a material which exhibits at least one distinctive property which is détectable 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 détection and/or authenti cation.

The radiation curable coating compositions described herein may be prepared by dispersing or mixing the platelet-shaped 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 ail other ingrédients or may be added at a later stage, i.e. after the formation of the liquid coating composition.

The present invention provides the methods described herein and the printing apparatuses described herein to produce optical .effect layers (OELs) on the substrates (x20> described herein. The shape of the coating layer (xl0) of the optical effect layers (OELs) described herein may be continuous or discontinuons. According to one embodiment, the shape of the coating layer (xlO) represent one or more indicia, dots and/or lines. The shape of the coating layer (xl 0) may consist of lines, dots and/or indicia being spaced apart from each other by a free area.

The substrate (x20) described herein is preferably selected from the group consisting of papers or other fibrous materials (including woven and non-woven frbrous materials), such as cellulose, paper-containing materials, glasses, metals, ceramîcs, plastics and polymers, metallized plastics or polymers, composite materials and mixtures or combinations of two or more thereof. Typical paper, paper-like or other frbrous 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 în 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(l,4-butylene terephthalate) (PBT), poly(ethylene 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 métal disposed continuously or discontinuously on their surface. Typical example 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 aforementîoned metals. The metallization of the plastic or polymer materials described hereabove may be done by an electrodeposition process, a highvacuum coating process or by a sputtering process. Typical examples of composite materials include without limitation multilayer structures or laminates of paper and at least one plastic or polymer materiai such as those described hereabove as well as plastic and/or polymer fibers incorporated in a paper-like or frbrous materiai 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, whîteners, processing aids, reinforcing or wet strengthening agents, etc. When the OELs produced according to the present invention are used for décorative or cosmetic purposes including for example fingemail lacquers, said OEL may be produced on other type of substrates including nails, artificial naîls or other parts of an animal or human being.

Should the OEL produced according to the present invention be on a security document, and with the aîm of further increasing the security level and the résistance against counterfeiting and illégal 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, toils, decals and combinations of two or more thereof. With the same aim of further increasing the security level and the résistance against counterfeiting and illégal reproduction of security documents, the substrate may comprise one or more marker substances or taggants and/or machine readable substances (e.g. luminescent substances, UV/visible/IR absorbing substances, magnetic substances and combinations thereof).

If desired, a primer layer may be applied to the substrate prior to the step a). This may enhance the quality ofthe OEL described herein or promote adhesion. Examples of such primer layers may be found in WO 2010/05S026 A2.

With the aim of increasing the durability through soiling or Chemical résistance and cleanliness and thus the circulation lifetime of an article, a security document or a décorative element or object comprising the OEL obtained by the method 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 ofthe OEL. When present, the one or more protective layers are typically made of protective vamishes. 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 préférable UV-Vis curable compositions. The protective layers are typically applied after the formation of the OEL.

The optical effect layer (OEL) or the substrate (x20) comprising the one or more optical effect layers (OELs) described herein may be further embossed for example by exerting pressure. The optical effect layer (OEL) described herein may be further and subsequently to the step of to at least partially curing the radiation curable coating composition described herein be at least partially overprînted with one or more inks or coating compositions so as to form one or more printed patterns or security features.

The present invention further provides optical effect layers (OELs) produced by the methods described herein and/or by using the printing apparatuses described herein. Also described herein are uses of the OELs described herein as anti-counterfeit means on documents and articles (in other words for protecting and authenticating documents and articles) as well as for décorative purposes.

The OEL described herein may be provided directly on a substrate on which it shall remain permanently (such as for banknote applications). Alternatively, an optical effect layer may also be provided on a temporary substrate for production purposes, from which the OEL îs subsequently removed. This may for example facilitate the production of the optical effect layer (OEL), particularly while the binder material is still în its fluid State. Thereafter, after hardening the coating composition for the production of the OEL, the temporary substrate may be removed from the OEL.

Alternatively, in another embodiment an adhesive layer may be present on the OEL or may be present on the substrate comprising OEL, said adhesive layer being on the side of the substrate opposite to the side where the OEL is provided or on the same side as the OEL and on top of the OEL. Therefore, an adhesive layer may be applied to the OEL or to the substrate, said adhesive layer being applied after the curing step has been completed. Such an article may be attached to ail 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 OELs are produced as described herein. One or more adhesive layers may be applied over the so produced optical effect layer.

Also described herein are substrates comprising more than one, i.e. two, three, four, etc. optical effect layers (OELs) obtained by the method described herein.

Also described herein are articles, in particular security documents, décorative éléments or objects, comprising the optical effect layer (OEL) produced according to the present invention. The articles, in particular security documents, décorative éléments or objects, may comprise more than one (for example two, three, etc.) OELs produced according to the present invention. As mentioned hereabove, the OEL produced according to the present invention may be used for décorative purposes as well as for protecting and authenticating a security document.

Typical examples of décorative éléments or objects include without limitation luxury goods, cosmetic packaging, automotive parts, electronic/electrical appliances, fumiture and fingemail articles.

Security documents include without limitation value documents and value commercial goods. Typical example 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 caïds, crédit cards, transactions cards, access documents or cards, entrance tickets, public transportation tickets, academie diploma or titles and the like, preferably banknotes, identity documents, right-conferring documents, driving licenses and crédit cards. The tenu “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 illégal 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 authentîcation 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 ofthe invention.

Altematively, the optical effect layer (OEL) described herein may be produced onto an auxiliary 5 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.

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

Further, ail documents referred to throughout this spécification are hereby incorporated by reference in their entirety as set forth in fnll herein.

EX AMPLES

The Examples and Comparative Examples hâve been carried out by using the UV-Vis curable screen-printing ink of the formula given m Table 1 and the first and second magnetic assemblies described herebelow.

Table 1

Epoxyacrylate oligomer (Allnex)	28 wt-%
Trimethylolpropane triacrylate monomer (Allnex)	19.5 wt-%
Tripropyleneglycol diacrylate monomer (Allnex)	20 wt-%
Genorad 16 (Rahn)	1 wt-%
Aerosil 200 (Evonik)	1 wt-%
Speedcure TPO-L (Lambson)	2 wt-%
Irgacure® 500 (IGM)	6 wt-%
Genocure® EPD (Rahn)	2 wt-%
BYK®371 (BYK)	2 wt-%
Tego Foamex N (Evonik)	2 wt-%
7-layer optically variable magnetic pigment particles (*)	16.5 wt-%

(*) 7-layer gold-to-green platelet-shaped optically variable magnetic pigment particles having a flake shape of diameter dso about 9.3 pm and thickness about 1 pm, obtained from JDS-Unîphase, Santa Rosa, CA.

Magnetic assembly according to the invention (Fig. 2A)

A magnetic assembly (200) configured for receiving a substrate (220) in an orientation substantially paraliel to a first plane was used to bi-axially orient the pigment particles according to the invention. The magnetic assembly (200) comprised a) a fïrst set (Si) comprising a first bar dipole magnet (231 ) and two second bar dipole magnets (232_a and 232b) and a second set (S2) comprising a first bar dipole magnet (231) and two second bar dipole magnets (232_a and 232b) and b) a first pair (P 1) of third bar dipole magnets (233_a and 233_b).

The upmost surface of the first bar dipole magnet (231) of the first and second sets (SI, S2)_s of the second bar dipole magnets (2 3 2_a and 232b) of the first and second set s(S 1, S2) and of the third bar dipole magnets (233_a and 233b) of the first pair (Pl) were flush with each other.

The third bar dipole magnet (233_a) was aligned with the second bar dipole magnet (232_a) of the first set (SI) and with the second bar dipole magnet (232_a) of the second set (S2) so as form a line. The third bar dipole magnet (23 3b) was aligned with the second bar dipole magnet (232b) of the first set (SI) and with the second bar dipole magnet (232_b) of the second set (S2) so as form a line. For each line described herein, tha third bar dipole magnets (233_a and 233_b) and the two second bar dipole magnets (232_a) were spaced apart by a third distance (d3) of 2 mm.

The first bar dipole magnets (231) of the first and second sets (SI, S2) had the following dimensions: first thickness (Ll) of 5 mm, first length (L4) of 60 mm and first width (L5) of 40 mm. Each ofthe second bar dipole magnets (232_a and 232_b) of the first and second set (SI, S 2) had the following dimensions: second thickness (L2) of 10 mm, second length (L6) of 40 mm and second width (L7) of 10 mm. Each of the third bar dipole magnets (233_a and 233_b) of the first pair (Pl) had the following dimensions: third thickness (L3) of 10 mm, third length (L8) of 20 mm and third width (L9) of 10 mm.

The first bar dipole magnet (231) of the first set (SI) and the second bar dipole magnets (232_a and 232_b) ofthe first set (SI) was aligned to form a column and the first bar dipole magnet (231) of the second set (S2) and the second bar dipole magnets (232_a and 232_b) of the second set (S2) was aligned to form a column. For each set (SI, S2) and each column described herein, the first bar dipole magnets (231 ) and the two second bar dipole magnets (232_a and 232_b) were spaced apart by a second distance (d2) of 2 mm.

The first bar dipole magnets (231) of the first and second sets (SI, S2) had their magnetic axis oriented to be substantially parallel to the first plane and substantially parallel to the substrate (220), wherein the first bar dipole magnet (231) of the first set (SI) had its magnetic direction opposite to the magnetic direction of the first bar dipole magnet (231) of the second set (S2), and were spaced apart by a first distance (dl) of 24 mm (corresponding to the sum of the third length (L8) and the two third distances (d3)).

The two second bar dipole magnets (232_a and 232_b) of the first and second set (SI, S2) had their magnetic axis oriented to be substantially perpendîcular to the first plane and substantially perpendîcular to the substrate (220). The South pôle of the second bar dipole magnet (232_a) of the first set (SI) pointed towards the first plane and towards the substrate (220), the North pôle of the second bar dipole magnet (232_b) ofthe first set (SI) pointed towards the first plane and towards the substrate (220), the North pôle of the first bar dipole magnets (231) of the first set (SI) pointed towards the second bar dipole magnet (232_b) ofthe first set (SI). The North pôle of the second bar dipole magnet (232_a) of the second set (S2) pointed towards the first plane and towards the substrate (220), the South pôle of the second bar dipole magnet (232_b) of the second set (S2) pointed towards the first plane and towards the substrate (220), the North pôle ofthe first bar dipole magnets (231) of the second set (S2) pointed towards the second bar dipole magnet (232_a) of the second set (S2).

The South pôle of the third bar dipole magnet (233_a) pointed towards the second bar dipole magnet (232_a) ofthe first set (SI), said second bar dipole magnet (232_a) having its South pôle pointing towards the substrate (220); and the North pôle of the third bar dipole magnet (233b) pointed towards the second bar dipole magnet (232_b) of the first set (SI), said second bar dipole magnet (232b) having its North pôle pointing towards the substrate (220).

The first bar dipole magnets (231) ofthe first and second sets (SI, S2), the second bar dipole magnets (232_a and 232_b) ofthe first and second sets (SI, S2) and the third bar dipole magnets (233_a and 233b) ofthe first pair (Pl) were made of NdFeB N 42 and were embedded in a nonmagnetic supportîng matrix (not shown) made of polyoxymethylene (POM) having the following dimensions: 115 mm x 115 mm x 12 mm.

The first bai' dipole magnets (231) of the first and second sets (SI, S2) had their magnetic axis oriented to be substantially parallel to the first plane and substantially parallel to the substrate (220), wherein the first bar dipole magnet (231 ) of the first set (S 1 ) had its magnetic direction opposite to the magnetic direction of the first bar dipole magnet (231 ) of the second set (S2) and were spaced apart by a first distance (dl) of 24 mm.

Magnetic assembly according to the prior art (Fig. 6A-B)

A comparative magnetic assembly (600) configured for receiving a substrate (620) în an orientation substantially parallel to a first plane was used to bi-axially orient the pigment particles. Said comparative magnetic assembly (600) comprised four bar dipole magnets (632ad) disposed in a staggered fashion according to Fig. 5 of EP 2 157 141 A. The four bar dipole magnets (632a-d) were identical to the second bar dipole magnets (232_a and 232_b) of the first and second set (SI, S2) described hereabove and were disposed in a staggered fashion, the distance (el) being 60 mm and the distance (e2) being about 40 mm.

Sample El and Comparative sample Cl (Fig. 7A)

For each sample, the UV-Vis curable screen printing ink of Table 1 was applied onto on a piece of fiduciary paper (BNP paper from Louisenthal, 100 g/m², 60 mm x 60 mm) so as to fonn a coating layer (40 mm x 40 mm), wherein said application step was carried out with a laboratory screen printing device using a T90 screen so as to form a coating layer having a thickness of about 20 pm.

While the coating layer was still in a wet and not yet cured state, the substrate (220, 620) was placed on top of the center of a supportîng plate (100 mm x 100 mm) made of high density polyethylene (HDPE). The supportîng plate carrying the substrate (220, 620) and the coating layer was independently moved at an approximate speed of 50 cm/sec above the magnetic assembly (200) illustrated in Fig. 2A for the sample El the magnetic assembly (600) illustrated in Fig. 6A for the comparative sample C1, wherein the substrate (220, 620) faced the magnetic assembly (200, 600) and the distance (h) ‘ between ihe upmost surface of the magnetic assembly (200, 600) and the substrate (220, 620) was 2 mm.

After having moved the supporting plate carrying the substrate (220, 620) and the coating layer at a distance (ds) of about 20 cm away from the magnetic assembly (200, 600), the coating layers were independently cured upon exposure during about 0.5 second to a UVLED-lamp (250, 650) from Phoseon (Type FireFlex 50 x 75 mm, 395 nm, 8W/cm2).

The resulting optical effect layer obtained with the magnetic assembly (200) according to the invention is shown in Fig. 7A (left) and the resulting optical effect layer obtained with the comparative magnetic assembly (600) is shown in Fig. 7A (right). As shown in Fig. 7A, the sample prepared according to the process of the invention consîsted of a homogeneous layer whereas the comparative sample suffered from the presence of a lighter and a darker band (area within the dotted rectangle) along the edge of the sample parallel to the motion of the substrate (620).

Sample E2 and Comparative sample C2 (Fig. 7B)

The sample E2 and comparative sample C2 were prepared according to the method described for El and Cl hereabove, except that the supporting plate carrying the substrate (220, 620) and the coating layer was moved three times above the magnetic assembly (200, 600) (forth/back/forth before the curing step.

The resulting optical effect layer obtained with the magnetic assembly (200) according to the invention is shown in Fig. 7B (left) and the resulting optical effect layer obtained with the comparative magnetic assembly (600) is shown in Fig. 7B (right). As shown in Fig. 7B, the sample prepared according to the process of the invention consisted of a homogeneous layer whereas the comparative sample suffered from the presence of a lighter and a darker band (area within the dotted rectangle) along the edge of the sample parallel to the motion of the substrate (620).

Sample E3 and Comparative sample C3 (Fig. 7C)

The sample E3 and comparative sample C3 were prepared according to the method described for E2 and C2 hereabove, except that the distance (h) between the upmost surface of the magnetic assembly (200, 600) and the substrate (220, 620) was 5 mm instead of 2 mm. The increase of the distance (h) was used to mimic an industrial process wherein grippers are conventionally used to hold the sheets or web of substrate in place during said industrial process.

The resulting optical effect layer obtained with the magnetic assembly (200) according to the invention is shown in Fig. 7C (left) and the resulting optical effect layer obtained with the comparative magnetic assembly (600) is shown in Fig. 7C (right). As shown in Fig. 7C, the sample prepared according to the process of the invention consisted of a homogeneous layer whereas the comparative sample suffered from the presence of two lighter and two darker bands (areas within the dotted rectangle) along the edges of the sample parallel to the motion of the substrate (620).

As shown in Fig. 7A-C (left), the optical effect layers (OELs) prepared according to the method of the present invention (E1-E3) with a magnetic assembly (200) according to the invention exhîbited a homogeneous aspect due to an optimal bi-axial orientation of the platelet-shaped magnetic or magnétisable pigment particles. In particular, the improved bi-axially orientation of the platelet-shaped magnetic or magnétisable pigment particles to hâve both their X-axes and Y-axes substantially parallel to the substrate surface allowed to produce optical effect layers exhîbiting a sheet-lîke surface over the whole surface. As shown in Fig. 7A-C (right), the optical effect layers prepared according to the comparative method of the prior art (C1-C3) with a comparative magnetic assembly (600) exhibited an inhomogeneous aspect.

As shown in Fig. 7A (left), a single pass on the magnetic assembly (200) of the present invention al lowed the préparation of a homogeneous optical effect layer. As shown in Fig. 7B (left), the increase of passes on the magnetic assembly (200) of the present invention also allowed the préparation of a homogeneous optical effect layer. As shown in Fig. 7C (left), an increase of the distance (h) between the magnetic assembly (200) and the substrate (220) still allowed the préparation of a homogeneous optical effect layer whereas the same increase of the distance (h) further negatively impacted the optical appearance of the optical effect layer obtained with the comparative method using a comparative magnetic assembly.

Claims

l. A magnetic assembiy (xOO) for producing an optical effect layer (OEL) on a substrate (x20), said magnetic assembiy (xOO) being configured for receiving the substrate (x20) in an orientation substantially parallel to a first plane and above the first plane, and further comprising: a) at least a first set (SI) and a second set (S2), each of the first and second sets (SI, S2) comprising:

one first bar dipole magnet (x31 ) having a first thickness (L l ), a first length (L4) and a first width (L5), and having its magnetic axis oriented to be substantially parallel to the first plane, two second bar dipole magnets (x32_a and x32t) having a second thickness (L2), a second length (L6) and a second width (L7), the two second bar dipole magnets (x32_a, x32b) having their upmost surfaces flush with each other, and having their magnetic axes oriented to be substantially perpendicular to the first plane, the first plane being located above the upmost surface of the two second bar dipole magnets (x32_a and x32b) the first bar dipole magnet (x31) ofthe first set (SI) having a magnetic direction opposite to the magnetic direction of the first bar dipole magnet (x31) of the second set (S2), the first bar dipole magnets (x31) of the first and second sets (SI, S2) being spaced apart by a first distance (dl), the first bar dipole magnet (x31 ) of the first set (S 1 ) having substantially the same first length (L4) and first width (L5) as the first bar dipole magnet (x31) of the second set (S2), and the two second bar dipole magnets (x32_a and x32b) of the first set (SI) having substantially the same second lengths (L6) and second widths (L7) as the two second bar dipole magnets (x32_aand x32b) of the second set (S2), the first bar dipole magnet (x31) and the second bar dipole magnets (x32_a and x32b) of each of the first and second sets (SI, S2) being aligned to form a column, in that the first bar dipole magnet (x31) of the first and second sets (S 1, S2) is respectively placed between and spaced apart from the second bar dipole magnets (x32_a and x32_b) by a second distance (d2), the first width (L5) and the second length (L6) being substantially the same, the North pôle of one second bar dipole magnet (x32_a and x32_b) of each of the first and second sets (S 1, S2) pointing towards the first plane as the North Pôle of the first bar dipole magnet (x31 ) poînting towards said one, and the South pôle of the other of the second bar dipole magnet (x32_a and x32_b) of each of the first and second sets (SI, S2) pointing towards the first plane and the South Pôle ofthe first bar dipole magnet (x31) pointing towards said other, and further comprising:

b) a first pair (Pl) of third bar dipole magnets (x33_a and x33_b) having a third thickness (L3), a third length (L8) and a third width (L9) and having their magnetic axes oriented to be substantially parallel to the first plane, the second width (L7) of the two second bar dipole magnets (x32_a and x32_b) of the first and second sets (SI, S2) having substantially the same value as the third width (L9) of the third bar dipole magnets (x33_a and x33_b), each of the third bar dipole magnets (x33_a and x33_b) being aligned with one second bar dipole magnet (x32_a and x32_b) of the first set (SI) and one second bar dipole magnet (x32_a and x32_b) of the second set (S2) so as to form two lines, the third bar dipole magnets (x33_a and x33_b) being placed between and spaced apart from the respective second bar dipole magnets (x32_a and x32_b) by a third distance (d3), the North pôles of the third bar dipole magnets (x33a and x33_b) respectively pointing towards one of the second bar dipole magnets (x32_a and x32_b) and the North Pôles of said ones of the second bar dipole magnets (x32_a and x32_b) pointing towards the first plane or the South pôles of the third bar dipole magnets (x33_a and x33_b) respectively pointing towards one of the second bar dipole magnets (x32_a and x32_b) and the South Pôles of said ones of the second bar dipole magnets (x32_a and x32_b) pointing towards the first plane, wherein the first bar dipole magnets (x31 ) of the first and second sets (S 1, S2), the second bar dipole magnets (x32_a and x32_b) of the first and second sets (SI, S2), and the third bar dipole magnets (x33_a and x33_b) are at least partially embedded in a non-magnetîc supportîng matrix.
2. The magnetic assembly (xOO) according to claim 1, wherein the first thickness (Ll) of the first bar dipole magnets (x31) of the first and second sets (SI, S2) is preferably equal to or smaller than the second thickness (L2) of the second bar dipole magnets (x32_a and x32_b) of the first and second sets (SI, S2); preferably wherein the ratio of the second thickness (L2) of the second bar dipole magnets (x32_a and x32_b) of the first and second sets (S l, S2) over the first thickness (Ll ) of the first bar dipole magnets- (x-31 ) of the first and second sets (SI, S2) (L2/L1) is equal to or smaller than 3 and greater than or equal to 1 (i.e. 1 < L2/L1 < 3);

the first thickness (L 1 ) of the first bar dipole magnets (x31 ) of the first and second sets (SI, S2) is preferably equal to or smaller than the third thickness (L3) of the third bar dipole magnets (x33_a and x33b) of the first pair (P 1); preferably wherein the ratio of the third thickness (L3) of the third bar dipole magnets (x33_a and x33b) of the first pair (Pl) over the first thickness (Ll) of the first bar dipole magnets (x31) of the first and second sets (S 1, S2) (L3/L1 ) is equal to or smaller than 3 and greater than or equal to 1 ( 1 < L3/L1 <3);

wherein the second distance (d2) between the first bar dipole magnet (x31 ) and the second bar dipole magnets (x32_a and x32b) is larger than or equal to 0 and smaller than or equal to /2 of the first thickness (Ll) of the first bar dipole magnets (x31) (0 < d2 < % LI); and wherein the third distance (d3) between the third bar dipole magnets (x33_a and x33b) of the first pair (Pl) and the second bar dipole magnets (x32_a and x32b) of the first and second sets (SI, S2) is larger than or equal to 0 and smaller than or equal to */2 of the first thickness (Ll) of the first bar dipole magnets (x31 ) (0 < d3 < VzLl).
3. The magnetic assembly (xOO) according to claim 1 or 2, wherein the npmost surface of the second bar dipole magnets (x32_a and x32b) are flush with the upmost surfaces of the third bar dipole magnets (x33_a and x33b).
4. The magnetic assembly (xOO) according to any one of claims 1 to 3, wherein the first distance (dl) between the first bar dipole magnets (x31) ofthe first and second sets (SI, S2) is greater than or equal to 15% of the first length (L4) and smaller than or equal to 150% of the first length (L4) (i.e. 0.15*L4<dl<1.5*L4), preferably greater than or equal to 25% ofthe first length (L4) and smaller than or equal to 120% ofthe first length (L4) (i.e. 0.25*L4<dl<1.2*L4), even more preferably greater than or equal to 25% of the first length (L4) and smaller than or equal to 80% of the first length (L4) (i.e. 0.25*L4<dl<0.8*L4).
5. The magnetic assembly (xOO) according to any one of claims 1 to 4, further comprising one or more combinations comprising:

i) a (2+i)th set (Sp+ΐ)) (i = 1, 2, etc.) comprising:

one further first bar dipole magnet (x31 ) having the first thickness (Ll ), the first length (L4) and the first width (L5), and having its magnetic axis oriented to be substantially parallel to the first plane, and two further second bar dipole magnets (x32_a and x32_b) having the second thickness (L2), the second length (L6) and the second width (L7), the two second bar dipole magnets (x32_a, x32_b) having their upmost surfaces flash with each other, and having their magnetic axes oriented to be substantially perpendicular to the first plane, the first bar dipole magnet (x31) of the (2+i)th set (S₂+>) having a magnetic direction opposite to the magnetic direction of the first bar dipole magnet (x31 ) of the (2+i-1 )th set (S2+1-1) the first bar dipole magnets (x31 ) of the (2+i)th and (2+i-1 )th sets (S₂+i, S2+1-1) being spaced apart by the first distance (dl), the first bar dipole magnet (x31) of the (2+i)th set (S2+O having substantially the same length (L5) and width (L4) as the first bar dipole magnet (x31) ofthe (2+i-l)th set (S₂+i-i), and the two second bar dipole magnets (x32_a, x32_b) of the (2+i)th set (Sp+p) having substantially the same lengths (L6) and widths (L7) as the two second bar dipole magnets (x32_a, x32_b) ofthe (2+i1 )th set (S₂+i-i), the first bar dipole magnet (x31) and the second bar dipole magnets (x32_a, x32_b) being aligned to form a column, in that the first bar dipole magnet (x31) of the (2+i)th set (S₂+i) is placed between and spaced apart from the second bar dipole magnets (x32_a, x32_b) by the second distance (d2), the first and second lengths (L4 and L6) being substantially the same, the North pôle of one of the second bar dipole magnets (x32_a, x32_b) ofthe (2+î)th set (S₂+i) pointing towards the first plane and the North Foie of the first bar dipole magnet (x31) pointing towards that second bar dipole magnet, and ii) a (1 +i)th pair (Pi+i) of third bar dipole magnets (x33_a and x33_b) having the third thickness (L3), the third length (L9) and the third width (L8) and having their magnetic axes oriented to be substantially paraliel to the magnetic axes of the third bar dipole magnets (x33_a and x33_b) of the (1+i-l )th pair (Pi+i-1), each of the third bar dipole magnets (x33_a and x33_b) being aligned with one second bar dipole magnet (x32_a and x32_b) of the (2+i)th set (S2+O and one second bar dipole magnet (x32_a and x32_b) of the (2+i-l)th set (S₂+m) so as to form two lines, the third bar dipole magnets (x33_a and x33_b) being placed between and spaced apart from the respective second bar dipole magnets (x32_a and x32_b) by the third distance (d3), the North pôles of the third bar dipole magnets (x33_a and x33_b) respectively pointing towards one of the second bar dipole magnets (x32_a and x32_b) of the (2+i)th and (2+i-l)th sets (S₂+i, S₂+i1) and the North Pôles of said ones of the second bar dipole magnets (x32_a and x32_b) pointing towards the first plane or the South pôles of the third bar dipole magnets (x33_a and x33_b) respectively pointing towards one of the second bar dipole magnets (x32_a and x32_b) ofthe (2+i)th and (2+i-l)th sets (Si+i, Si+i-i) and the South Pôles of said ones ofthe second bar dipole magnets (x32_a and x32b) pointing towards the first plane, wherein the first bar dipole magnets (x31) of the (2+i)th set (S2+0, the second bar dipole magnets (x32_a and x32_b) of the (2+i)th set (Sp+i)), and the third bar dipole magnets (x33_a and x33_b) of the ( 1 +i)th pair (Pi+i) are at least partially embedded in the non-magnetic supporting matrix.
6. A printing apparatus comprising the magnetic assembly (xOO) according to any one of claims 1 to 5 being mounted in the vicinîty of a transferring device preferably selected from the group consisting of chains, belts, cylinders and combinations thereof.
7. A method for producing an optical effect layer (OEL) on a substrate (x20) comprising the steps of:

i) applying on a substrate (x20) surface a radiation curable coating composition comprising platelet-shaped magnetic or magnétisable pigment particles, wherein an X-axis and a Y-axis define a plane of prédominant extension of the particles, said radiation curable coating composition being in a first, iîquîd state so as to form a coating layer (xl 0);

ii) exposing the coating layer (xlO) to a magnetic field of the magnetic assembly (xOO) recited in any one of claims 1 to 5 so as to bî-axially orient at least a part of the platelet-shaped magnetic or magnétisable pigment particles;

iii) at least partially curing the radiation curable coating composition of step ii) to a second, solid state so as to fix the platelet-shaped magnetic or magnétisable pigment particles in their adopted positions and orientations.
8. The method according to claim 7, further comprising a further step of exposing the coating layer (xlO) to a magnetic field of a magnetic-field-generating device so as to re-orient at least a part of the platelet-shaped magnetic or magnétisable particles, said further step being carried out subsequently to step ii).
9. The method according to claim 8, wherein a step of selectîvely at least partially curing one or more first areas of the coating layer (xlO) of the radiation curable coating composition of step ii) is carried out so as to fix at least a part of the platelet-shaped magnetic or magnétisable particles in their adopted positions and orientations, such that one or more second areas of the coating layer (xlO) remain unexposed to irradiation, said step being carried out priorto, partially simultaneously with or subsequently to the step of claim 9 of further exposing the coating layer (xlO) to the magnetic field of the magnetic-field-generating device.

ΙΟ. The method according to claim 7, wherein the coating layer (xlO) is exposed, in a single step, to the interaction of magnetic fields of the magnetic assembly (xOO) recited in any one of claims l to 7 and a magnetic-field-generating device comprising one or more hard magnetic magnets, the magnetic-field-generating device being mounted on a rotating magnetic cylinder (x60) or being a moveable magnetic-field-generating device.
11. The method according to claim 7, wherein the coating layer (xlO) is exposed, in a single step, to the interaction of the magnetic fields of the magnetic assembly (xOO) recited in any one of claims 1 to 6 and one or more soft magnetic plates carrying one or more indicia in the form of voids and/or indentations and/or protrusions, said one or more soft magnetic plates being placed on a rotating magnetic cylinder (x60) or being placed on a moveable device below the substrate (x20).
12. The method according to any one of claims 7 to 11, wherein a distance (h) between the upmost surface of the first bar dipole magnets (x31 ) and the substrate is greater than 0 and smaller than or equal to about 20 mm, preferably smaller than or equal to about 10 mm and greater than about 2 mm.
13. The method according to any one of claims 7 to 12, wherein step iii) is carried out by UV-Vis light radiation curing.
14. The method according to any one or claims 7 to 13, wherein at least a part of the plateletshaped magnetic or magnétisable particles is constituted by platelet-shaped optically variable magnetic or magnétisable pigment particles, preferably selected from the group consisting of magnetic thin-film interférence pigments, magnetic cholesteric liquid crystal pigments and mixtures thereof.