EA038016B1 - Processes for producing optical effect layers - Google Patents

Abstract

The invention relates to the field of processes and printing apparatuses for producing optical effect layers (OEL) comprising magnetically oriented platelet-shaped magnetic or magnetizable pigment particles on a substrate. In particular, the invention relates to processes using printing apparatuses comprising a first magnetic-field-generating device mounted on a transferring device (TD) and a static second magnetic-field-generating device for producing said OELs as anti-counterfeit means on security documents or security articles or for decorative purposes.

Description

The technical field to which the invention relates

The present invention relates to the field of methods and printers for producing optical effect layers (OEL) containing magnetically oriented lamellar magnetic or magnetizable pigment particles. In particular, the present invention provides methods and printers for magnetic orientation of lamellar magnetic or magnetizable pigment particles in a coating layer to produce OELs and the use of said OELs as anti-counterfeiting agents on security documents or security articles, as well as for decorative purposes.

Background of the invention

It is known in the art to use paints, compositions, coatings or layers containing oriented magnetic or magnetizable pigment particles, in particular also optically variable magnetic or magnetizable pigment particles, for the production of security elements, for example in the field of security documents. Coatings or layers containing oriented magnetic or magnetizable pigment particles are disclosed, for example, in US 2570856, US 3676273, US 3791864, US 5630877 and US 5364689. attracting special attention, used to protect the protected documents, disclosed in documents WO 2002/090002 A2 and WO 2005/002866 A1.

Security features, for example, for security documents, can be broadly divided into latent security features, on the one hand, and explicit security features, on the other hand. The protection afforded by covert security features is based on the principle that these features are difficult to detect and usually require specialized equipment and knowledge to detect them, while overt security features are based on the concept of easy detection by the unarmed human senses; for example, such features can be visible and / or detectable through tactile sensations and still be difficult to manufacture and / or copy. However, the effectiveness of explicit security features is more dependent on their easy recognition as a security feature.

Magnetic or magnetizable pigment particles in printing inks or coatings allow the creation of magnetically induced images, patterns and / or designs by applying an appropriately structured magnetic field causing the local orientation of the magnetic or magnetizable pigment particles in an uncured (i.e. wet) coating with subsequent hardening of the coating. The result is a stationary and stable magnetically induced image, pattern or pattern. Materials and techniques for orienting magnetic or magnetizable pigment particles in coating compositions are disclosed in US Pat. No. 2,418,479; US 2,570,856; US 3791864, DE 2006848-A, US 3676273, US 5364689, US 6103361, EP 0406667 B1; US 2002/0160194; US 2004/0009308; EP 0710508 A1; WO 2002/09002 A2; WO 2003/000801 A2; WO 2005/002866 A1; WO 2006/061301 A1. Thus, magnetically induced patterns can be obtained which are highly counterfeit resistant. The security element in question can only be manufactured if there is access both to the magnetic or magnetizable pigment particles or the corresponding ink, and to the specific technology used to print said ink and to orient said pigment in the printed ink.

The methods and devices described herein above use magnetic assemblies to uniaxially orient the platy magnetic pigment particles. The uniaxial orientation of the magnetic pigment particles results in the principal axes of adjacent particles being parallel to each other and to the magnetic field, while their minor axes in the plane of the pigment particles are not parallel or much less constrained by the applied magnetic field.

With the aim of producing coatings or layers containing biaxially oriented magnetic or magnetizable pigment particles, methods have been developed to create time-dependent, direction-varying magnetic fields of sufficient intensity, thereby providing biaxial orientation of magnetic or magnetizable pigment particles.

WO 2015/086257 A1 discloses an improved method for producing an optical effect layer (OEL) on a substrate, said method comprising two steps of magnetic orientation, said steps consisting of i) subjecting a coating composition containing plate-like magnetic or magnetizable particles pigment, the effect of dynamic, i.e. directionally changing magnetic field of the first magnetic field generating device with biaxial orientation of at least a portion of the lamellar magnetic or magnetizable pigment particles, and ii) subjecting the coating composition to a static magnetic field of the second magnetic field generating device with uniaxial reorientation of at least measure of a portion of the lamellar magnetic or magnetizable pigment particles in accordance with the design carried by said second magnetic field generating device. Considering that the method disclosed in WO 2015/086257 A1 allows optical effect layers to be obtained showing improved brightness and contrast compared to the prior art, said method requires two independent steps, where the first step requires

- 1 038016 additional space for pre-alignment of magnetic or magnetizable pigment particles. This requirement is cumbersome for high-speed industrial printing equipment, as it requires additional space that is difficult to access for modern printing equipment, resulting in adaptations of current equipment and high costs.

Therefore, there remains a need for improved methods of producing optical effect layers (OEL), which methods are mechanically reliable, easy to implement with industrial high-speed printing equipment, in particular rotating magnetic cylinders for orientation, without resorting to problematic, tedious and costly modifications of the specified equipment. This need persists, in particular, for an improved method of producing optical effect layers (OELs) exhibiting an eye-catching dynamic effect to provide, in combination, high resolution and high contrast.

Brief description of the invention

Accordingly, it is an object of the present invention to overcome the disadvantages of the prior art. This is achieved by providing a method for producing an optical effect layer (OEL) on a substrate (x10), said method comprising the steps of:

a) applying to the surface of a substrate (x10) a coating composition containing lamellar magnetic or magnetizable pigment particles to form a coating layer (x20) on said substrate (x10), said coating composition being in the first state,

b) placing a substrate (x10) carrying a coating layer (x20) on a first magnetic field generating device (x30) providing a first magnetic field vector component, said first magnetic field generating device (x30) being installed on a device for transfer (TD), thereby subjecting the platy magnetic or magnetizable pigment particles to the specified first component of the magnetic field vector, while moving the specified substrate (x10), the carrier layer (x20) of the coating, and the specified first device (x30), generating a magnetic field, on close distance to a static second magnetic field generating device (x40), said second magnetic field generating device (x40) providing a second component of the magnetic field vector, thereby exposing the lamellar magnetic or magnetizable pigment particles to the time-dependent magnetic field generated formed by the first and second components of the magnet vector field, with biaxial orientation of at least part of the lamellar magnetic or magnetizable pigment particles, while the ratio of the magnetic flux density of the first device (x30), generating a magnetic field, and the magnetic flux density of the second device (x40), generating a magnetic field, is less than approximately 4.0, preferably less than about 1.9, and more preferably from about 1.5 to about 0.5; and

c) allowing the coating composition to cure in the second state, fixing the lamellar magnetic or magnetizable pigment particles in their positions and orientations.

Also described herein are optical effect layers (OELs) obtained by the method described herein, and security documents, as well as decorative elements and objects containing one or more optical OELs described herein.

Also described herein are methods of making a security document or decorative element or object, including a) providing a security document or decorative element or object, and b) providing an optical effect layer such as described herein, in particular such as obtained by the method, described herein, so that it is included in the security document or decorative element or object.

Also described herein are printing devices comprising a transfer device (TD) described herein, preferably a rotating magnetic cylinder (RMC) described herein, and at least one of second devices (x40) generating a magnetic field, described herein, wherein said transfer device (TD), preferably said rotating magnetic cylinder (RMC), comprises at least one of the first magnetic field generating devices (x30) described herein and mounted thereon.

Also, this document describes the applications of printers to obtain the optical effect layers (OEL) described in this document.

The method provided by the present invention is mechanically reliable, easy to implement with industrial high-speed printing equipment, without resorting to problematic, tedious and costly modifications to said equipment.

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Brief Description of Drawings

Next, the optical effect layers (OEL) described herein, as well as their manufacture will be described in more detail with reference to the drawings and specific embodiments, which indicate the following.

FIG. 1 schematically illustrates the exposure of a substrate (110) carrying a coating layer (120) to i) a first magnetic field generating device (130) mounted on a transfer device (TD), in particular a rotating magnetic cylinder (RMC), and ii) a static second magnetic field generating device (140), where the substrate (110) carrying the coating layer (120) simultaneously moves with the first magnetic field generating device (130) close to the static second magnetic generating device (140) field. Solidification of the coating layer (120) is achieved by means of an optical effect layer (OEL) hardener (150).

FIG. 2 is a schematic top view of a combination comprising a first magnetic field generating device (230) providing a first time independent magnetic field vector component and a static second magnetic field generating device (240) providing a second magnetic field vector component. The first device (230) generating a magnetic field is a bar dipole magnet, which synchronously and simultaneously moves with the substrate (210) carrying the coating layer (220) (not shown in Fig. 2), close to the second device (240 ) generating a magnetic field.

FIG. 3 schematically illustrates the magnetic fields of a first magnetic field generating device (330) providing a first time independent magnetic field vector component (H1), magnetic fields of a second magnetic field generating device (340) providing a second magnetic field vector component (H2) , and the resulting magnetic field (H3), formed by the first and second components of the magnetic field vector, i.e. resulting from the addition of the H1 and H2 components of the vector.

FIG. 4A is a schematic illustration of a method for orienting platy magnetic or magnetizable pigment particles contained in a coating layer (420) on a substrate (410) using a transfer device (TD), in particular a linear magnetic transfer device (LMTD), according to the present invention, with This method includes the step of simultaneously moving (see gray arrow) the substrate (410) carrying the coating layer (420) with the first device (430) generating a magnetic field close to the static second device (440) generating a magnetic field containing two dipole bar magnets (441a and 441b).

FIG. 4B is a schematic cross-sectional view of the first and second magnetic field generating devices (430, 440) of FIG. 4A. The rod dipole magnet of the first magnetic field generating device (430) is contained in a holder (431), said holder being placed over a support block (432) and a rail (433). Two dipole bar magnets (441a and 441b) of the second magnetic field generating device (440) are inserted into two holders (442a and 442b) fixed to the frame (443a-c).

FIG. 4C is a schematic cross-sectional view of the first magnetic field generating device (430) of FIG. 4A-B. The first magnetic field generating device (430) is contained in a holder (431) held by a support block (432) and a rail (433) to be moved close to the static second magnetic field generating device, whereby the substrate (410), a carrier layer (420) of the coating is placed on top of the specified holder (431).

FIG. 5A-D schematically illustrate a top view (FIGS. 5A and 5C) and a cross-sectional view (5B and 5D) of a first magnetic field generating device (530) similar to that shown in FIG. 4AC and a Hall magnetometer (560) (FIGS. 5A-5B) for measuring the magnetic flux density of the first magnetic field generating device (530) or coating layer (520) on the substrate (510) (FIGS. 5C-D).

FIG. 6A schematically illustrates a second magnetic field generating device (640) similar to that shown in FIG. 4A-C, and a Hall magnetometer (660) (FIG. 6A) used to measure the magnetic flux density of the second magnetic field generating device (640).

FIG. 6B-C schematically illustrate a top view (FIG. 6B) and cross-section (6C) of a second magnetic field generating device (640) similar to that shown in FIG. 4A-C, and a Hall magnetometer (660) used to measure the magnetic flux density of the second magnetic field generating device (640).

FIG. 7A schematically illustrates the operating principles of conoscopic reflectometry used to measure the directions of the reflected beam in the OEL shown herein.

FIG. 7B schematically illustrates the complete configuration of a reflective conoscopic reflectometer as used to determine the orientation of pigment particles in an OEL.

FIG. 8 schematically illustrates a method for analyzing an OEL obtained with a device according to the present invention by means of a conoscopic reflectometer.

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FIG. 9A-D schematically illustrate the resulting reflected light spot on the focal plane (960) (FIGS.9A and 9B) and the polar angle distribution (FIGS.9C and 9D) of an OEL made of oriented magnetic or magnetizable pigment particles with a high degree of biaxial alignment. (FIGS.9A and 9C), and an OEL made from oriented magnetic or magnetizable pigment particles with a low degree of biaxial alignment (FIGS.9B and 9D), using the conoscopic reflectometry measurement principle for the analysis of optical effect layers (OEL) obtained using the device.

Detailed description

Definitions

For the interpretation of the meaning of the terms discussed in the description and set forth in the claims, the following definitions should be used.

In the context of this document, the singular form of an object indicates one or more objects, and does not necessarily limit the object to a single number.

In the context of this document, the term at least means one or more one, for example one, or two, or three.

In the context of this document, the term approximately means that a specified amount or value may have a specific specified meaning or some other meaning adjacent to it. In general, the term approximate, denoting a specific value, is intended to indicate a range within ± 5% of the value. As one example, the phrase about 100 means a range of 100 ± 5, i.e. range from 95 to 105. In general, when using the term approximately, it can be expected that similar results or effects according to the present invention can be obtained in the range of ± 5% of the specified value.

In the context of this document, the term and / or means that either all or only one of the elements of the specified group may be present. For example, A and / or B will mean only A or only B, or both A and B. In the case of only A, this term also covers the possibility of the absence of B, that is, only A, but not B.

The term containing in the context of this document is non-exclusive and subject to change. Thus, for example, a coating composition containing compound A may contain other compounds in addition to A. However, the term comprising also encompasses, like its specific embodiment, the more restrictive meanings consisting essentially of and consisting of, so that, for example, a composition comprising A, B and optionally C may also (mainly) consist of A and B or (mainly) consist of A, B and C.

The term optical effect layer (OEL) in the context of this document means a coating or layer that contains oriented lamellar magnetic or magnetizable pigment particles and a binder, wherein said lamellar magnetic or magnetizable pigment particles are oriented by a magnetic field, and the oriented lamellar magnetic or magnetizable pigment particles are fixed / immobilized in their orientation and position (i.e. after solidification / curing) to form a magnetically induced image.

The term coating composition refers to any composition that is capable of forming an optical effect layer (OEL) on a solid substrate and that can be applied, preferably, but not exclusively, by printing. The coating composition contains the lamellar magnetic or magnetizable pigment particles described herein and the binder described herein.

In the context of this document, the term wet refers to a coating layer that has not yet cured, for example a coating in which the lamellar magnetic or magnetizable pigment particles can still change their positions and orientations due to external forces acting on them.

In the context of this document, the term marks will mean discontinuous layers such as drawings, including without limitation symbols, alphanumeric characters, ornaments, letters, words, numbers, logos and graphics.

The term hardening is used to mean a process in which the viscosity of the coating composition increases in a first physical state that is not yet hardened (i.e., wet), transforming it into a second physical state, i.e. a hardened or solid state in which the lamellar magnetic or magnetizable pigment particles are fixed / immobilized in their current positions and orientations and can no longer move or rotate.

The term security document refers to a document that is typically protected against counterfeiting or falsification by at least one security feature. Examples of protected documents include, but are not limited to, valuable documents and valuable commercial goods.

The term security feature is used to refer to an image, pattern, or graphic element that can be used for authentication purposes.

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When the present description concerns preferred embodiments / features, combinations of these preferred embodiments / features should also be considered disclosed as long as the combination of preferred embodiments / features is technically relevant.

The present invention provides methods for producing optical effect layers (OEL) on substrates. The method according to the present invention includes the steps:

a) coating the surface of a substrate (x10) described herein with a coating composition containing the lamellar magnetic or magnetizable pigment particles described herein to form a coating layer (x20) described herein on said substrate (x10 ), while the specified composition for coating is in the first state,

b) placing a substrate (x10) carrying a coating layer (x20) on a first magnetic field generating device (x30) described herein and providing a first magnetic field vector component described herein, said first device (x30 ) generating a magnetic field is mounted on a transfer device (TD), thereby exposing the platy magnetic or magnetizable pigment particles to the specified first component of the magnetic field vector, while moving the specified substrate (x10), the carrier layer (x20) of the coating, and the specified first a device (x30) generating a magnetic field, close to a static (i.e., not moving with a transfer device (TD)) second device (x40), generating a magnetic field described in this document, while the specified second device ( x40), which generates a magnetic field, provides the second component of the magnetic field vector described in this document, thereby th lamellar magnetic or magnetizable pigment particles to a time-dependent magnetic field generated by the first and second components of the magnetic field vector described herein, with biaxial orientation of at least a portion of the lamellar magnetic or magnetizable pigment particles, wherein the ratio of the magnetic flux density of the first the magnetic field generating device (x30) and the magnetic flux density of the second magnetic field generating device (x40) is less than about 4.0, preferably less than about 1.9, and more preferably from about 1.5 to about 0.5 , and

c) allowing the coating composition to cure in the second state, fixing the lamellar magnetic or magnetizable pigment particles in their positions and orientations.

The present invention provides a reliable and simple implementation of a method for producing optical effect layers (OEL). Magnetic orientation of the lamellar magnetic or magnetizable pigment particles on the substrate is carried out by placing the substrate (x10) carrying the coating layer (x20) containing said lamellar magnetic or magnetizable pigment particles on the first device (x30) generating a magnetic field installed on the transfer device (TD) described herein, preferably on a rotating magnetic cylinder (RMC) described herein, and subjecting them to a static second magnetic field generating device, the first magnetic field generating device (x30) and the substrate ( x10), bearing the coating layer (x20), are simultaneously moved with the first device (x30) generating the magnetic field and with the transfer device (TD), and the said second device generating the magnetic field is a static device, i.e. e. it does not move with the transfer device (TD).

Since the substrate (x10) carrying the coating layer (x20) moves simultaneously with the first magnetic field generating device (x30), while said first magnetic field generating device (x30) provides the first time-independent magnetic field vector component, lamellar magnetic or magnetizable pigment particles are exposed to said first magnetic field vector component, wherein said first magnetic field vector component is time independent in the reference coating layer structure, preferably time independent within a plane that is anchored in the reference coating layer structure ...

The present invention takes advantage of the synchronous and simultaneous movement of the substrate (x10) carrying the coating layer (x20) containing the lamellar magnetic or magnetizable pigment particles with the first device (x30) generating a magnetic field close to the static second device (x40) generating a magnetic field (i.e. through the magnetic field of a static second device (x40) generating a magnetic field), while said second device (x40) generating a magnetic field does not move with the transfer device (TD) and provides the second component magnetic field vector. The resulting magnetic field, formed by the first and second components of the magnetic field vector, provides biaxial orientation of at least part of the lamellar magnetic or magnetizable pigment particles. During

5 038016 of the method described herein, the lamellar magnetic or magnetizable pigment particles are exposed to a time-dependent resulting magnetic field, which is the sum of the vector of the first and second components of the magnetic field vector, and move within said non-uniform resulting magnetic fields. By time-dependent magnetic field is meant that along the path followed by the individual lamellar magnetic or magnetizable pigment particles of the coating layer, the magnetic field is time-dependent (i.e. changing with time) in a direction or time-dependent (i.e. i.e., changing with time) in direction and intensity in the reference structure of the coating layer, preferably time-dependent (i.e., changing with time) within a plane that is anchored in the reference structure of the coating layer. Thus, at least a portion of the lamellar magnetic or magnetizable pigment particles of the coating layer tend to align, resulting in biaxial orientation of at least a portion of said lamellar magnetic or magnetizable particles, i. E. an orientation in which the two largest major axes of said lamellar pigment particles are bounded. When creating the desired effect in the not yet cured (ie, wet) coating layer, the coating composition is partially or completely cured, permanently fixing / immobilizing the relative position and orientation of the lamellar magnetic or magnetizable pigment particles in the OEL.

The transfer device (TD) described herein can be a rotating magnetic orientation cylinder (RMC) or a linear magnetic transfer device (LMTD), such as, for example, a linear guide. Preferably, the transfer device (TD) described herein is a rotatable magnetic orientation cylinder (RMC).

As shown in FIG. 1, a first magnetic field generating device (x30) described herein is mounted on a transfer device (TD), a rotating magnetic orientation cylinder (RMC) described herein, said rotating magnetic orientation cylinder (RMC) is part of a rotary, industrial sheet-fed or web-fed printing press that continuously operates at high printing speeds, in particular the first device (x30) that generates a magnetic field is mounted on the annular grooves or lateral grooves of a rotating magnetic cylinder (RMC) ... A rotating magnetic orientation cylinder (RMC) containing the first device (x30) generating a magnetic field described in this document is intended to be used in part or in combination with a part, or it is a part of printing or coating equipment containing a static second device (x40) generating a magnetic field, described herein, for orienting plate-like magnetic or magnetizable pigment particles in a coating layer.

The method described herein includes the step a) applying to the surface of the substrate (x10) described herein, a coating composition containing the lamellar magnetic or magnetizable pigment particles described herein to form a coating layer (x20), when the specified composition for coating is in the first physical state, which allows it to be applied as a layer, and which is in an uncured (i.e. wet) state, while the lamellar magnetic or magnetizable pigment particles can move and rotate within the binder material. Since the coating composition described herein must be applied to the surface of a substrate (x10), the coating composition comprises at least a binder material such as those described herein and platelet-like magnetic or magnetizable pigment particles, said composition for The coating is in a form that can be processed on the desired printing or coating equipment. Preferably, said step a) is carried out by a printing process, preferably selected from the group consisting of screen printing, rotogravure printing, flexographic printing, inkjet printing and gravure printing (also referred to in the art as copper plate printing and engraved embossing printing). steel stamp), more preferably selected from the group consisting of rotogravure printing, screen printing, rotogravure printing and flexographic printing, and even more preferably selected from the group consisting of rotogravure printing, screen printing, rotogravure printing and flexographic printing.

Screen printing (also referred to in the art as screen printing) is a patterned patterning process in which ink is transferred to a surface through a pattern supported by a fine silk mesh, one or more filaments made from synthetic fibers such as, for example, polyamides or polyesters, or metal filaments pulled tightly over a frame made, for example, of wood or metal (for example, aluminum or stainless steel). Alternatively, the screen printing mesh can be chemically etched, laser etched, or electroplated with a porous metal foil, such as stainless steel foil. Mesh pores are blocked

- 6 038016 in areas without an image and left open in an area with an image, the carrier of the image is called stencil. Screen printing can be flat or rotary.

Screen printing is further described, for example, in The Printing ink manual, R.H. Leach and R.J.

Pierce, Springer Edition, 5 ^oe edition, pp. 58-62 and Printing Technology, JM Adams and PA Dolin , Delmar

Thomson Learning, 5 ^oe edition, pp. 293-328.

Rotary gravure printing (also referred to in the art as intaglio printing) is a printing process in which image elements are engraved onto the surface of a cylinder. Areas without an image are at a constant baseline. Before printing, the entire printing plate (non-printable and printable elements) is covered with ink and filled with ink. The ink is removed from the non-image area with a sponge or knife before printing so that ink remains only in the cells. The image is transferred from the cells to the substrate under the influence of pressure, usually in the range of 2-4 bar, and adhesion forces between the substrate and the ink. The term rotogravure printing does not encompass other gravure printing processes (also referred to in the art as engraved steel stamping or engraved copper mold printing processes) that are based, for example, on different types of ink. More details are provided in the Handbook of print media, Helmut Kipphan, Springer Edition, p. 48 and in The Printing ink manual, RH Leach and RJ Pierce, Springer Edition, 5 ^oe edition, pp. 42-51.

In flexographic printing, preferably a doctor blade unit is used, preferably a doctor blade chamber, anilox roll and a plate cylinder. Anilox roll preferably has small cells, the volume and / or density of which determines the degree of ink application. The squeegee blade is positioned opposite the anilox roller and removes excess ink at the same time. The anilox roller transfers the ink to the plate cylinder, which ultimately transfers the ink to the substrate. A specific design can be achieved using a specially designed photopolymer printing plate. Form cylinders can be made of polymeric or elastomeric materials. Polymers are mainly used as a photopolymer in printing plates and sometimes as a seamless coating on a roll. Photopolymer printing plates are made from light-sensitive polymers that harden when exposed to ultraviolet (UV) light. Photopolymer printing plates are cut to the required size and placed in the UV light exposure unit. One side of the plate is fully exposed to UV light to allow the plate base to cure or cure. Then the printing plate is turned over, the reverse side of the blank is placed on top of the uncured side, and the printing plate is further exposed to UV light. This allows the plate to solidify in the image areas. The plate is then processed to remove uncured photopolymer from the non-image areas, which reduces the surface of the plate in these non-image areas. After processing, the plate is dried and exposed to an additional dose of UV light to cure the entire plate. Preparation of the printing cylinders for flexographic printing described in Printing Technology, JM Adams and PA Dolin , Delmar Thomson Learning, 5 ^oe edition, pp. 359-360, and in The Printing ink manual, RH Leach and RJ. Pierce, Springer Edition, 5 ^oe edition, pp. 33-42.

The coating composition described herein, as well as the (x20) coating layer described herein, contain lamellar magnetic or magnetizable pigment particles. Preferably, the lamellar magnetic or magnetizable pigment particles described herein are present in an amount of from about 5 to about 40 wt%, more preferably from about 10 to about 30 wt%, with the weight percentages based on the total weight of the composition for cover.

Unlike needle-shaped pigment particles, which can be considered as quasi-one-dimensional particles, lamellar pigment particles are quasi-two-dimensional particles, due to the large aspect ratio of their sizes. A lamellar pigment particle can be considered a two-dimensional structure where the X and Y dimensions are substantially larger than the Z dimension. Lamellar pigment particles are also referred to in the art as flattened particles or flakes. Such pigment particles can be described by a major X-axis corresponding to the longest dimension crossing the pigment particle, and a second Y-axis perpendicular to X and crossing the pigment particle. In other words, the XY plane roughly defines the plane formed by the first and second longest pigment particle sizes, without taking into account the Z dimension.

The lamellar magnetic or magnetizable pigment particles described herein, due to their non-spherical shape, exhibit anisotropic reflectivity to incident electromagnetic radiation for which the hardened / hardened binder material is at least partially transparent. In the context of this document, the term anisotropic reflectivity means that the fraction of incident radiation at a first angle reflected by a particle in a certain direction (view) (second angle) depends on the orientation of the particles, i.e. that a change in the orientation of a particle with respect to the first angle can lead to different amounts of reflection in the direction of view.

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The OEL described herein contains lamellar magnetic or magnetizable pigment particles that, due to their shape, are characterized by anisotropic reflectivity. In the OELs described herein, the lamellar magnetic or magnetizable pigment particles described herein are dispersed in a coating composition containing a hardened binder that fixes the orientation of the lamellar magnetic or magnetizable pigment particles. The binder is at least in its hardened or solid state (also referred to herein as the second state) at least partially transparent to electromagnetic radiation in the wavelength range of 200 to 2500 nm, i. E. within the range of wavelengths commonly referred to as the optical spectrum and which contains the infrared, visible and UV portions of the electromagnetic spectrum. Accordingly, particles contained in the binder in its cured or solid state, as well as their orientation-dependent reflectivity, can be sensed through the binder at certain wavelengths within a given range. Preferably, the cured binder is at least partially transparent to electromagnetic radiation in the wavelength range of 200 to 800 nm, more preferably 400 to 700 nm. In this document, the term transparent means that the transmission of electromagnetic radiation through the 20 μm layer of hardened binder present in the OEL (excluding the lamellar magnetic or magnetizable pigment particles, but including all other optional components of the OEL, if such components are present) is at least at least 50%, more preferably at least 60%, even more preferably at least 70% at the wavelength (s) in question. This can be determined, for example, by measuring the transmittance of a test piece of hardened binder (excluding lamellar magnetic or magnetizable pigment particles) according to well-known test methods such as DIN 5036-3 (1979-11). If the OEL serves as a covert security feature, then technology will generally be required to detect the (full) optical effect produced by the OEL under appropriate lighting conditions, including a selected wavelength in the invisible region; however, said detection requires that the wavelength of the incident radiation be selected outside the visible range, for example, in the near UV range.

Suitable examples of the lamellar magnetic or magnetizable pigment particles described herein include, without limitation, pigment particles comprising a magnetic metal selected from the group consisting of cobalt (Co), iron (Fe), and nickel (Ni); a magnetic alloy of iron, manganese, cobalt, nickel, or a mixture of two or more of them; magnetic oxide of chromium, manganese, cobalt, iron, nickel, or a mixture of two or more of them; or a mixture of two or more of them. The term magnetic in relation to metals, alloys and oxides refers to ferromagnetic or ferrimagnetic metals, alloys and oxides. Magnetic oxides of chromium, manganese, cobalt, iron, nickel, or mixtures of two or more of these can be pure or mixed oxides. Examples of magnetic oxides include, but are not limited to, iron oxides such as hematite (Fe ₂ O ₃ ), magnetite (Fe ₃ O ₄ ), chromium dioxide (CrO ₂ ), magnetic ferrites (MFe ₂ O ₄ ), magnetic spinels (MR2O4), magnetic hexaferrites (MFe ₁₂ O ₁₉ ), magnetic orthoferrites (RFeO ₃ ), magnetic garnets M ₃ R ₂ (AO ₄ ) ₃ , where M means divalent metal, R means trivalent metal, and A means tetravalent metal.

Examples of the lamellar magnetic or magnetizable pigment particles described herein include, without limitation, pigment particles comprising a magnetic layer M made of one or more magnetic metals such as cobalt (Co), iron (Fe), or nickel (Ni); and also a magnetic alloy of iron, cobalt or nickel, wherein said magnetic or magnetizable pigment particles can be multilayer structures containing one or more additional layers. Preferably, one or more additional layers are A layers independently made of one or more materials selected from the group consisting of metal fluorides such as magnesium fluoride (MgF ₂ ), silicon oxide (SiO), silicon dioxide (SiO ₂ ) , titanium oxide (TiO ₂ ) and alumina (Al ₂ O ₃ ), more preferably silicon dioxide (SiO ₂ ); or layers B independently made of one or more materials selected from the group consisting of metals and metal alloys, preferably selected from the group consisting of reflective metals and reflective metal alloys, and more preferably selected from the group consisting of aluminum ( Al), chromium (Cr) and nickel (Ni), and even more preferably aluminum (Al); or a combination of one or more layers A, such as the layers described herein above, and one or more layers B, such as the layers described herein above. Typical examples of lamellar magnetic or magnetizable pigment particles that are multilayer structures described herein above include, but are not limited to, A / M multilayer structures, A / M / A multilayer structures, A / M / B multilayer structures, A / B multilayer structures. / M / A, multilayer structures A / B / M / B, multilayer structures A / B / M / B / A, multilayer structures B / M, multilayer structures B / M / B, multilayer structures B / A / M / A , multilayer structures B / A / M / B, multilayer structures B / A / M / B / A /, where layers A, magnetic layers M and layers B are selected from those described in

- 8 038016 above.

The coating composition described herein may contain plate-like optically variable magnetic or magnetizable pigment particles and / or plate-like magnetic or magnetizable pigment particles having no optically variable properties. Preferably, at least a portion of the lamellar magnetic or magnetizable pigment particles described herein are lamellar optically variable magnetic or magnetizable pigment particles. In addition to the overt protection provided by the color-changing property of optically variable magnetic or magnetizable pigment particles, which makes it easy to detect, recognize and / or distinguish an article or security document to which an ink has been applied, a coating composition or coating layer containing optically variable magnetic or the magnetizable pigment particles described herein, from their possible counterfeits, using the naked human senses, as a machine-readable tool for OEL recognition, the optical properties of optically variable magnetic or magnetizable pigment particles can also be used. Thus, the optical properties of optically variable magnetic or magnetizable pigment particles can simultaneously be used as a hidden or semi-hidden security feature in an authentication process in which the optical (eg spectral) properties of the pigment particles are analyzed.

The use of plate-like optically variable magnetic or magnetizable pigment particles in coating layers to create OEL increases the importance of OEL as a security feature in applications for security documents, since such materials are intended for printing security documents and are not available for commercial use by the general public.

As noted above, preferably at least a portion of the lamellar magnetic or magnetizable pigment particles are formed by lamellar optically variable magnetic or magnetizable pigment particles. They are more preferably selected from the group consisting of magnetic thin film interference pigment particles, magnetic cholesteric liquid crystal pigment particles, interference coated pigment particles containing a magnetic material, and mixtures of two or more thereof.

Magnetic thin film pigment interference particles are known to those skilled in the art and are disclosed, for example, in US Pat. No. 4,838,648; WO 2002/073250 A2; EP 0686675 B1; WO 2003/000801 A2; US 6838166; WO 2007/131833 A1; EP 2402401 A1 and in the documents referred to therein. Preferably, the magnetic thin film interference pigment particles are pigment particles having a five-layer Fabry-Perot structure and / or pigment particles having a six-layer Fabry-Perot structure and / or pigment particles having a seven-layer Fabry-Perot structure.

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

Preferred six-layer Fabry-Perot structures consist of multi-layer absorber / dielectric / reflector / magnetic material / dielectric / absorber structures.

Preferred seven-layer Fabry-Perot structures are composed of absorber / dielectric / reflector / magnetic material / reflector / dielectric / absorber multilayer structures such as described in US Pat. No. 4,838,648.

Preferably, the reflector layers described herein are independently made from one or more materials selected from the group consisting of metals and metal alloys, preferably selected from the group consisting of reflective metals and reflective metal alloys, more preferably selected from the group consisting of aluminum (Al), silver (Ag), copper (Cu), gold (Au), platinum (Pt), tin (Sn), titanium (Ti), palladium (Pd), rhodium (Rh), niobium ( Nb), chromium (Cr), nickel (Ni) and their alloys, even more preferably selected from the group consisting of aluminum (Al), chromium (Cr), nickel (Ni) and their alloys, and even more preferably aluminum (Al). Preferably, the dielectric layers are independently made from one or more materials selected from the group consisting of metal fluorides such as magnesium fluoride (MgF ₂ ), aluminum fluoride (AlF ₃ ), cerium fluoride (CeF ₃ ), lanthanum fluoride (LaF ₃ ) , sodium aluminofluorides (for example, Na ₃ AlF ₆ ), neodymium fluoride (NdF ₃ ), samarium fluoride (SmF ₃ ), barium fluoride (BaF ₂ ), calcium fluoride (CaF ₂ ), lithium fluoride (LiF), as well as metal oxides such as silicon oxide (SiO), silicon dioxide (SiO2), titanium oxide (TiO2), aluminum oxide (Al2O3), more preferably selected from the group consisting of magnesium fluoride (MgF2), and silicon dioxide (SiO _2), and even more preferably magnesium fluoride (MgF ₂ ). Preferably, the absorbent layers are independently made from one or more materials selected from the group consisting of aluminum (Al), silver (Ag), copper (Cu), palladium (Pd), platinum (Pt), titanium (Ti), vanadium ( V),

- 9 038016 iron (Fe), tin (Sn), tungsten (W), molybdenum (Mo), rhodium (Rh), niobium (Nb), chromium (Cr), nickel (Ni), oxides of these metals, sulfides of these metals , carbides of these metals, as well as alloys of these metals, more preferably selected from the group consisting of chromium (Cr), nickel (Ni), oxides of these metals and alloys of these metals, and even more preferably selected from the group consisting of chromium (Cr), nickel (Ni) and alloys of these metals. Preferably, the magnetic layer contains nickel (Ni), iron (Fe) and / or cobalt (Co); and / or a magnetic alloy containing nickel (Ni), iron (Fe) and / or cobalt (Co); and / or a magnetic oxide containing nickel (Ni), iron (Fe) and / or cobalt (Co). If magnetic thin film interference pigment particles containing a seven-layer Fabry-Perot structure are preferred, it is particularly preferred that the magnetic thin-film interference pigment particles comprise a seven-layer Fabry-Perot structure absorber / dielectric / reflector / magnetic material / reflector / dielectric / absorber consisting of multilayer structure Cr / MgF2 / Al / Ni / Al / MgF2 / Cr.

The magnetic thin film pigment interference particles described herein can be multilayer pigment particles that are considered safe for human health and the environment and are based on, for example, Fabry-Perot five-layer structures, Fabry-Perot six-layer structures and Fabry-seven-layer structures. Feather, wherein said pigment particles comprise one or more magnetic layers containing a magnetic alloy having a substantially nickel-free composition comprising from about 40 to about 90 wt% iron, from about 10 to about 50 wt% chromium and from about 0 up to about 30 wt.% aluminum. Typical examples of multilayer pigment particles that are considered safe for human health and the environment can be found in EP 2402401 A1, the contents of which are incorporated herein by reference in their entirety.

The magnetic thin film pigment interference particles described herein are typically prepared by conventional techniques for depositing various desired layers onto a web. After deposition of the required number of layers, for example by physical vapor deposition (PVD), chemical vapor deposition (CVD), or electrolytic deposition, the set of layers is removed from the web, either by dissolving the separating layer in a suitable solvent or by peeling off the material from the web. The material thus obtained is then broken up into flakes, which must be further processed by crushing, milling (such as, for example, jet milling processes) or any suitable method designed to obtain pigment particles of the desired size. The resulting product includes flat flakes with ragged edges, irregular shapes and varying aspect ratios. Further information on the preparation of suitable magnetic thin film pigment interference particles can be found, for example, in documents EP 1710756 A1 and EP 1666546 A1, the contents of which are incorporated herein by reference.

Suitable magnetic cholesteric liquid crystal pigment particles exhibiting optically variable characteristics include, but are not limited to, magnetic single layer cholesteric liquid crystal pigment particles and magnetic multilayer cholesteric liquid crystal pigment particles. Such pigment particles are disclosed, for example, in documents WO 2006/063926 A1, US 6582781 and US 6531221. Document WO 2006/063926 A1 discloses monolayers and pigment particles obtained therefrom with increased gloss and color-changing properties, as well as additional special properties such as magnetization. The disclosed monolayers and pigment particles which are obtained therefrom by grinding said monolayers include a three-dimensionally crosslinked cholesteric liquid crystal mixture and magnetic nanoparticles. In documents US 6582781 and US 6410130 discloses lamellar cholesteric multilayer pigment particles which comprise the sequence A ¹ / B / A ² where A ¹ and A ² may be identical or different and each comprises at least one cholesteric layer, and B is an intermediate layer that absorbs all the light, or some portion of light transmitted by the layers A ¹ and A ^2, and provides the magnetic properties of said intermediate layer. US Pat. No. 6,531,221 discloses lamellar cholesteric multilayer pigment particles comprising the sequence A / B and optionally C, where A and C are absorbent layers containing magnetic particles of pigment and B is a cholesteric layer.

Suitable interference coated pigments containing one or more magnetic materials include, but are not limited to, structures consisting of a substrate selected from the group consisting of a core coated with one or more layers, wherein at least one of the core or one or more layers has magnetic properties. For example, suitable interference coated pigments comprise a core made of a magnetic material such as described herein above, said core being coated with one or more layers of one or more metal oxides, or having a core structure, made of synthetic or natural mica, layered silicates (such as talc, kaolin and sericite), glasses (such as borosilicates), silicas (SiO ₂ ), aluminum oxides (Al ₂ O ₃ ), titanium oxides (TiO ₂ ), graphites and mixtures of two or more of them. Moreover, one or more additional layers, such as coloring layers, may be present.

The surface of the magnetic or magnetizable pigment particles described herein can be treated in order to protect them from any damage that may occur in the coating composition and coating layer, and / or to facilitate their inclusion in the specified coating composition and coating layer; generally, corrosion inhibiting materials and / or wetting agents can be used.

In addition, after applying the coating composition described herein to the surface of the substrate described herein to form a coating layer (step a)), the substrate carrying the coating layer is placed over the first magnetic field generating device (x30) mounted on a transfer device (TD) described herein, preferably on a rotating magnetic cylinder (RMC) described herein. The substrate (x10) supporting the coating layer (x20) can be directly placed on top of the first magnetic field generating device (x30), i.e. the substrate is in direct contact with the first magnetic field generating device (x30), or a gap may be located between the substrate (x10) and the first magnetic field generating device (x30).

In one embodiment, and as shown in FIG. 4A-C, a substrate (x10) carrying a coating layer (x20) is placed over the first magnetic field generating device (x30) with a gap between the substrate (x10) and the first magnetic field generating device (x30), said gap can be obtained using one or more holders, one or more plates, or one or more spacers (x31). The holder, plate or one or more spacers (x31) are independently preferably made / made of one or more non-magnetic materials selected from the group consisting of materials with low conductivity, non-conductive materials and mixtures thereof, such as, for example, engineering plastics and polymers, titanium, titanium alloys, and austenitic steels (i.e. non-magnetic steels). Engineering plastics and polymers include, but are not limited to, polyaryletherketones (PAEK) and their derivatives, polyetheretherketones (PEEK), polyetherketoneketones (PEKK), polyetheretherketone ketones (PEEKK), and polyetheretherketone ketone ketone (PEKEKK); polyacetals, polyamides, polyesters, polyethers, ester copolymers, polyimides, polyetherimides, high density polyethylene (HDPE), ultra high molecular weight polyethylene (UHMWPE), polybutylene terephthalate (PBT), polypropylene, copolymer-butadiene-styrene-butadiene-styrene ABS), fluorinated and perfluorinated polyethylenes, polystyrenes, polycarbonates, polyphenylene sulfide (PPS) and liquid crystal polymers. The preferred materials are PEEK (polyetheretherketone), POM (polyoxymethylene), PTFE (polytetrafluoroethylene), Nylon® (polyamide) and PPS. Preferably, the holder, plate or one or more spacers (x31) are independently made / made of more than one titanium-based material, since these materials have the advantage of excellent mechanical resistance and low electrical conductivity. The holder, plate or one or more spacers (x31) can also be made of aluminum or aluminum alloys, the advantage of which is easy processing.

Since the substrate (x10) carrying the coating layer (x20) is located on top of the first magnetic field generating device (x30), said coating layer (x20) is exposed to the magnetic field of the static second device (x40) generating the magnetic field.

The method described herein includes the step of causing the coating layer (x20) to solidify in the first state to the second state, while fixing / immobilizing the lamellar magnetic or magnetizable pigment particles in their positions and orientations. The step of providing solidification is carried out using a block (x50) to ensure solidification. Thus, it should be noted that the coating composition described herein must be in the first state, i. E. a liquid or pasty state in which the coating composition is not yet hardened and wet or soft enough that the lamellar magnetic or magnetizable pigment particles dispersed in the coating composition can freely move, rotate and / or orient themselves when exposed to a magnetic field, and a second solidified (eg, solid or solid-like) state in which the lamellar magnetic or magnetizable pigment particles are fixed or immobilized in their respective positions and orientations.

Such first and second states are preferably created using a particular type of coating composition. For example, components of the coating composition other than the lamellar magnetic or magnetizable pigment particles can take the form of an ink or coating composition such as for security purposes, such as for printing banknotes. The aforementioned first and second states can be achieved by using a material that exhibits an increase in viscosity in response to stimulation such as temperature change or exposure to electromagnetic radiation. Thus, if the liquid binder is hardened or hardened, said binder is converted to the second state, i. E. a hardened or solid state in which the lamellar magnetic or magnetisable particles of the pigment are fixed in their current positions and orientations and can no longer move or rotate within the binder material. As is known to those skilled in the art, the ingredients contained in a paint or coating composition to be applied to a surface such as a substrate and the physical properties of said paint or coating composition must meet the requirements of the process used to transfer the paint or coating composition to substrate surface. Therefore, the binder contained in the coating composition described herein is generally selected from binders known in the art, and the choice depends on the coating or printing process used to apply the paint or coating composition, and selected solidification process.

The curing step generally can be any step that increases the viscosity of the coating composition such that a substantially solid material is formed adhered to the substrate. The step of providing solidification may include a physical process based on evaporation of a volatile component such as a solvent and / or evaporation of water (i.e., physical drying). In this case, hot air, infrared radiation, or a combination of hot air and infrared radiation can be used. Alternatively, the curing process may involve a chemical reaction such as curing, polymerizing, or crosslinking the binder and optional initiator compounds and / or optional crosslinking compounds contained in the coating composition. Such a chemical reaction can be initiated by heat or IR radiation as described above for physical curing processes, but can preferably include the initiation of a chemical reaction by a radiation mechanism, including without limitation curing by exposure to radiation in the ultraviolet and visible regions (hereinafter referred to in this document as UV / Vis curing) and electron beam curing (electron beam curing), oxypolymerization (oxidative reticulation, usually caused by the combined action of oxygen and one or more catalysts, preferably selected from the group consisting of from cobalt-containing catalysts, vanadium-containing catalysts, zirconium-containing catalysts, bismuth-containing catalysts and manganese-containing catalysts); crosslinking reactions or any combination thereof.

The curing step described herein (step c)) may be of a purely physical nature, for example in cases where the coating composition contains a polymeric binder and a solvent and is applied at high temperatures. Then, the lamellar magnetic or magnetizable pigment particles are oriented at high temperature by applying a magnetic field, and the solvent is evaporated, followed by cooling of the coating composition. Thus, the coating composition is cured and the orientation of the pigment particles is fixed.

Alternatively, and preferably, the curing of the coating composition involves a chemical reaction, for example through curing, which is not reversible by a simple increase in temperature (eg, to 80 ° C) that can occur during normal use of the security document. The terms curing or curable refers to processes involving the chemical reaction, crosslinking, or polymerization of at least one component in the applied coating composition so that it is converted into a polymer material having a higher molecular weight than the starting materials. Preferably, curing causes the formation of a stable three-dimensional polymer network. This curing is typically caused by the application of an external stimulus to the coating composition. Preferably, the coating composition is selected from the group consisting of radiation curable compositions, heat curing compositions, oxidation curing compositions, and combinations thereof.

Radiation curing is particularly preferred, and UV / VIS curing is even more preferred as these technologies advantageously result in very fast curing processes and therefore significantly shorten the production time of any article containing the OEL described in this document. In addition, radiation curing has the advantage of providing an almost instantaneous increase in the viscosity of the coating composition after exposure to radiation causing curing, thereby minimizing any further particle movement. As a consequence, it is generally possible to avoid any loss of orientation after the magnetic orientation step. Particularly preferred is radiation curing by photopolymerization with actinic light having a UV or blue wavelength component of the electromagnetic spectrum (typically 200 to 650 nm, more preferably 200 to 420 nm). Equipment for providing UV-visible curing may include a high power light emitting diode (LED) lamp, or an arc lamp such as a medium pressure mercury arc lamp (MPA).

- 12 038016 or a metal vapor discharge lamp as a source of actinic radiation. Accordingly, particularly preferred are coating compositions selected from the group consisting of radiation curable compositions. Curing by radiation, in particular curing by exposure to UV and visible radiation, advantageously leads to an instant increase in the viscosity of the coating composition after exposure to radiation, thus preventing any further movement of the pigment particles and subsequently any loss of information after stage of magnetic orientation. Preferably, the step of providing curing (step c)) is performed by exposure to UV and visible radiation (i.e. curing by exposure to UV and visible radiation) or by exposure to electron beam (i.e., curing by exposure to electron beam radiation), more preferably under the influence of radiation in the UV and visible region.

Thus, suitable coating compositions according to the present invention include radiation curable compositions that can be cured by exposure to UV-visible radiation (hereinafter referred to herein as curable by UV-visible radiation) or electronically radiation (hereinafter referred to as EL). According to one particularly preferred embodiment of the present invention, the coating composition described herein is a UV-visible radiation curable coating composition. Curing by exposure to UV and visible radiation advantageously allows very fast curing processes, and therefore significantly reduces the time to obtain the OEL described in this document, documents and products, as well as documents containing the specified OEL.

Preferably, the UV / VIS curable coating composition contains one or more compounds selected from the group consisting of radically curable compounds and cationic curable compounds. The UV / VIS curable coating composition described herein can be a hybrid system and comprise a mixture of one or more cationic curable compounds and one or more radical curable compounds. Cationically curable compounds are cured by cationic mechanisms, typically involving radiation activation of one or more photoinitiators that release cationic particles such as acids, which in turn initiate cure to react and / or crosslink the monomers and / or oligomers to allow the coating composition to cure in this way. Radically curable compounds are cured by free radical mechanisms, typically involving radiation activation of one or more photoinitiators, thereby generating radicals, which in turn initiate polymerization to cause the coating composition to cure in this way. Various photoinitiators can be used depending on the monomers, oligomers, or prepolymers used to form the binder contained in the UV-visible coating compositions described herein. Suitable examples of free radical photoinitiators are known to those skilled in the art and include, but are not limited to, acetophenones, benzophenones, benzyldimethylketals, alpha amino ketones, alpha hydroxy ketones, phosphine oxides, and phosphine oxide derivatives, and mixtures of two or more thereof. Suitable examples of cationic photoinitiators are known to those skilled in the art and include, but are not limited to, onium salts such as organic iodonium salts (e.g. diaryloiodonium salts), oxonium (e.g. triaryloxonium salts) and sulfonium salts (e.g. triarylsulfonium salts), as well as mixtures of two or more of them. Other examples of photoinitiators used can be found in standard scientific manuals. It may also be advantageous to include a sensitizer with one or more photoinitiators to achieve effective curing. Typical examples of suitable photosensitizers include, but are not limited to isopropylthioxanthone (ITX), 1-chloro-2propoxythioxanthone (CPTX), 2-chlorothioxanthone (CTX), and 2,4-diethylthioxanthone (DETX), as well as mixtures of two or more thereof. The one or more photoinitiators contained in the UV / VIS curable coating compositions are preferably present in a total amount of from about 0.1 to about 20 wt%, more preferably from about 1 to about 15 wt%, the weight percentages are based on the total weight of the UV / VIS curable coating compositions.

Alternatively, a polymeric thermoplastic binder or thermosetting material can be used. Unlike thermosetting materials, thermoplastic resins can re-melt and harden when heated and cooled without undergoing any significant changes in properties. Typical examples of a thermoplastic resin or polymer include, but are not limited to, polyamides, polyesters, polyacetals, polyolefins, styrene polymers, polycarbonates, polyarylates, polyimides, polyether ether ketones (PEEK), polyether ketone ketones (PEKK), polyphenylene based resins (e.g., polyphenylene polyphenylene, polyphenylene oxides

- 13 038016 polyphenylene sulfides), polysulfones and mixtures of two or more of them.

The OEL preparation method described herein includes partly simultaneously with step b) or after step b), preferably partly simultaneously, the step of hardening (step c)) of the coating composition. The step of allowing the coating composition to solidify fixes the lamellar magnetic or magnetizable pigment particles at their positions and orientations in the desired pattern to form an OEL, thereby converting the coating composition to the second state described herein. However, the time from the end of step b) to the start of step c) is preferably relatively short in order to avoid any deorientation and loss of information. Typically, the time between the end of step c) and the start of step c) is less than 1 minute, preferably less than 20 seconds, more preferably less than 5 seconds. It is particularly advantageous if there is essentially no time interval at all between the end of the alignment step b) and the start of the cure step c), i. E. if step c) immediately follows step b) or is already starting when step b) is still in progress (partly simultaneously). By partly simultaneously it is to be understood that both steps are carried out partly at the same time, i. E. the execution times of each of the stages partially overlap. In the context described in this document, when solidification is carried out partially simultaneously with step b), it should be understood that solidification takes effect after the start of the orientation process, so that the lamellar magnetic or magnetizable pigment particles are oriented before the complete or partial solidification of the OEL, in particular when the resulting magnetic field (H3) generated by the first and second components of the magnetic field vector (i.e., obtained by adding the vectors H1 and H2) described herein is greater than zero, preferably greater than 50 mT. As noted herein, the hardening step (step c)) can be carried out using various means or processes, depending on the binder contained in the coating composition, which also contains lamellar magnetic or magnetizable pigment particles.

The 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 to adjust the physical, rheological and chemical parameters of the coating composition, such as viscosity (e.g., solvents, thickeners, and surfactants), consistency (e.g., anti-settling agents, fillers and plasticizers), foaming properties (e.g. anti-foaming agents), lubricating properties (waxes, oils), UV resistance (photostabilizers), adhesion properties, antistatic properties, storage stability (polymerization inhibitors), etc. The additives described herein can be present in the coating composition in amounts and forms known in the art, including so-called nanomaterials, in which at least one of the additive dimensions is in the 11000 nm range.

The coating composition described herein may further comprise one or more additives, including but not limited to compounds and materials that are used to adjust the physical, rheological, and chemical parameters of the composition, such as viscosity (e.g., solvents and surfactants), consistency (e.g. anti-settling agents, fillers and plasticizers), foaming properties (e.g. anti-foaming agents), lubricating properties (waxes), reactivity and UV resistance (photosensitizers and photostabilizers) and adhesive properties, etc. The additives described herein can be present in the coating compositions described herein in amounts and forms known in the art, including in the form of so-called nanomaterials in which at least one of the particle sizes is in range 1-1000 nm.

The coating composition described herein may further comprise one or more marker substances or markers and / or one or more machine-readable materials selected from the group consisting of magnetic materials (other than the magnetic or magnetizable pigment particles described herein), luminescent materials, electrically conductive materials, and materials that absorb infrared radiation. In the context of this document, the term machine-readable material refers to a material that exhibits at least one characteristic that is detectable by a device or machine, and which can be contained in a coating to provide a method for authenticating said coating or an article containing said coating by using specific equipment for its detection and / or authentication.

The coating compositions described herein can be prepared by dispersing or mixing the magnetic or magnetizable pigment particles described herein and, if present, one or more additives in the presence of the binder described herein, thus forming liquid compositions. If present, one or more photoinitiators may be added to the composition either during the dispersing or mixing step of all the remaining ingredients, or may be added at a subsequent step, ie after the liquid coating composition has been formed.

Since the substrate (x10) carrying the coating layer (x20) moves simultaneously with the first device (x30) generating the magnetic field, the method described herein includes the step of moving them close to the static second device (x40) generating the magnetic field. the field described herein, wherein the substrate (x10) carrying the coating layer (x20) is placed on top of the first device (x30) generating a magnetic field. As shown in FIG. 2 and 3, a first magnetic field generating device (x30) provides a first magnetic field vector component that is time independent in the reference layer structure of the coating, preferably time independent within a plane that is anchored in the reference layer structure (x20 ) coverage.

The substrate (x10), the carrier layer (x20) of the coating described in this document, and the first device (x30) generating the magnetic field, synchronously and simultaneously move a close distance to the static (i.e. not moving with the transfer device (TD )) a second device (x40) generating a magnetic field (i.e. through a static magnetic field, i.e. not moving with the transfer device (TD) described herein, a second device (x40) generating a magnetic field) providing a second component of the magnetic field vector, which is time-dependent in the reference structure of the coating layer (x20), preferably time-dependent within a plane that is anchored in the reference structure of the coating layer (x20), as the coating layer (x20) moves close distance to the specified static second device (x40) generating a magnetic field. The lamellar magnetic or magnetizable pigment particles are thereby exposed to / placed in the conditions of the generated magnetic field formed by the first and second components of the magnetic field vector, while the specified magnetic field that occurs is time-dependent (changing with time) in the direction or time-dependent (changing over time) in direction and intensity (see FIG. 3), with biaxial orientation of at least a portion of said lamellar magnetic or magnetizable pigment particles while the coating composition is still in a wet (i.e., not yet cured) state.

As shown in FIG. 3, the first component (H1) of the magnetic field vector of the first magnetic field generating device (330) is constant over time in the reference structure of the coating layer and moves (as illustrated by the row of arrows in FIG. 3) simultaneously and synchronously with the substrate (x10) carrying the coating layer (x20) in the reference structure, the second device generating the magnetic field. The second component (H2) of the magnetic field vector of the second magnetic field generating device (340) is not substantially parallel to the first component (H1) of the magnetic field vector, preferably substantially perpendicular to the first component (H1) of the magnetic field vector of the first device (330) a magnetic field. The second component (N2) magnetic field vector of the second device (340) generating a magnetic field varies in intensity (alternatively varied in intensity and direction) in the space, with the maximum intensity (H2 _sha x) is in the center of the two dipole bar magnets shown in fig. 2 (241a and 241b, Fig. 2). Thus, a substrate (x10) carrying a coating layer (x20) moving a close distance to a second magnetic field generating device (x40) will be exposed to a temporarily varying (H2) intensity due to the movement of said substrate. When the substrate (x10) carrying the coating layer (x20) and the first magnetic field generating device (330) simultaneously move close to the second magnetic field generating device (340), the lamellar magnetic or magnetizable pigment particles contained in the layer (x20) coatings are exposed to an inhomogeneous magnetic field (H3) generated by the first and second components of the magnetic field vector, i.e. obtained as a result of adding vectors H1 and H2, i.e. they are exposed to a time-dependent magnetic field that varies at least in direction or varies in direction and intensity (see FIG. 3) in the reference structure of the coating layer, preferably time-dependent within a plane that is anchored in the reference structure of the coating layer , with biaxial orientation of the lamellar magnetic or magnetizable pigment particles of the specified layer (x20) of the coating.

A wide variety of optical effect layers (OELs) can be produced for decorative and security purposes using the method described herein. Prior art magnetic field generating devices that provide uniaxial orientation of lamellar magnetic or magnetizable pigment particles can be used as first magnetic field generating devices (x30), including, for example, dipole magnets, quadrupole magnets, and combinations thereof. The substrate (x10) carrying the coating layer (x20) described herein is simultaneously moved with the first magnetic field generating device (x30) mounted on the transfer device (TD) described herein, preferably on a rotating magnetic cylinder ( RMC) described in this document, at a close distance to the static second device (x40) generating a magnetic field, and thus through the magnetic field of said second device (x40), generating a magnetic field, the said first the device (x30) that generates the magnetic field is not itself a rotating magnet. Typical examples of suitable first devices (x30) generating a magnetic field include those described herein.

An OEL known as flip flop effects (also referred to in the art as a switching effect) can be obtained. Flip flop effects include a first printed portion and a second printed portion separated by a transition, with the pigment particles aligned parallel to the first plane in the first portion and the flakes in the second portion aligned parallel to the second plane. Methods and magnets for producing flip flop effects are disclosed, for example, in US 2005/0106367 and EP 1819525 B1.

Optical effects known as rolling band effects disclosed in US 2005/0106367 can also be obtained. The rolling strip effect is based on the orientation of the pigment particles to simulate a curved surface across the coating. The observer sees a zone of specular reflection, which shifts to the side or towards the observer when the image is tilted. The pigment particles are aligned in a curved manner, either in a convex curvature (also referred to in the art as negative curvature orientation) or in a concave curvature (also referred to in the art as positive curvature orientation). Methods and magnets for producing rolling strip effects are disclosed, for example, in EP 2263806 A1, EP 1674282 B1, EP 2263807 A1, WO 2004/007095 A2, WO 2012/104098 A1 and WO 2014/198905 A2.

Optical effects known as jagged effects can also be obtained. Jagged effects include pigment particles oriented so that along a particular viewing direction, they give visibility to the underlying surface of the substrate so that marks or other features present on or in the surface of the substrate become apparent to the observer while they obstruct visibility along the other. directions of observation. Methods for producing jagged effects are disclosed, for example, in US Pat. Nos. 8025952 and EP 1819525 B1.

Optical effects known as moving ring effects can also be obtained. Moving ring effects consist of optically illusory images of objects such as funnels, cones, balls, circles, ellipses, and hemispheres that appear to move in any x-y direction, depending on the tilt angle of the specified optical effect layer. Methods and magnets for producing moving ring effects are disclosed, for example, in EP 1710756A1, US 8343615, EP 2306222A1, EP 2325677 A2, WO 2011/092502 A2 and US 2013/084411.

Optical effects can also be obtained to give the optical impression of a pattern of moving bright and dark areas when the effect is tilted. A method and magnets for obtaining these optical effects are disclosed, for example, in WO 2013/167425 A1.

Optical effects can also be obtained to provide the optical impression of a loop-shaped body, the size of which changes when the effect is tilted. Methods and magnets for producing these optical effects are disclosed, for example, in co-pending applications EP15189955.6, EP15193837.0 and EP16157815.8.

Optical effects can also be obtained to provide an optical impression of one or more loop-shaped bodies, the shape of which changes as the optical effect layer is tilted. A method and magnets for producing these optical effects are disclosed, for example, in co-pending application EP16190044.4.

The first device (x30) that generates a magnetic field described herein may comprise a magnetic plate carrying one or more reliefs, engravings, or cutouts. WO 2005/002866 A1 and WO 2008/046702 A1 describe examples of such engraved magnetic plates.

In contrast to uniaxial orientation, in which the lamellar magnetic or magnetizable pigment particles are oriented in such a way that only their main axis is limited by the component of the magnetic field vector, the implementation of biaxial orientation means that the orientation of the lamellar magnetic or magnetizable pigment particles is ensured in such a way that both of their main the X and Y axes are limited. Such biaxial orientation is achieved according to the present invention by exposing / conditioning and moving the substrate (x10) carrying the coating layer (x20) with the first magnetic field generating device (x30) described herein close to the static second device (x40) generating a magnetic field (i.e. through the magnetic field of a second static device (x40) generating a magnetic field). Accordingly, the specified second device (x40), generating a magnetic field, should be designed in such a way that along the path of movement along which the individual lamellar magnetic or magnetizable particles of the pigment of the coating layer follow, the second component of the magnetic field vector changes at least in the direction or changes in direction and intensity in the reference structure of the coating layer (x20), preferably within a plane that is anchored in the reference structure of the coating layer (x20). Biaxial orientation aligns the planes of the lamellar magnetic or magnetizable pigment particles in such a way that said planes are oriented so as to be locally substantially parallel to each other.

Biaxial orientation of the lamellar magnetic or magnetizable pigment particles can be accomplished by simultaneously moving the substrate (x10) carrying the coating layer (x20) with the first magnetic field generating device (x30) mounted on the transfer device (TD) described herein. preferably on a rotating magnetic cylinder (RMC) described herein at an acceptable speed close to a static second magnetic field generating device (x40) such as described in EP 2157141 A1. Such devices provide a magnetic field that changes its direction, while the lamellar magnetic or magnetizable pigment particles move close to the specified devices, causing the lamellar magnetic or magnetizable pigment particles to rapidly oscillate until both major axes, the X-axis and the Y-axis, are stabilized. , i.e. the lamellar magnetic or magnetizable pigment particles vibrate until they arrive at a stable leaf-like formation with their respective X and Y axes planarized in these two dimensions. As shown in FIG. 5 of EP 2157141, the magnetic field generating device described herein comprises a linear arrangement of at least three magnets that are staggered or in a zigzag pattern, the magnetic axis of each of said three magnets being substantially perpendicular to the substrate surface (x10), and said at least three magnets on one side of the feed path have the same polarity, which is opposite to the polarity of the magnet (s) on the opposite side of the staggered feed path (as shown in Fig. 5, the indicated at least three magnets on one side of the infeed path have the same polarity, being on opposite sides of the infeed path, with the magnets on one side of the infeed path having the same polarity, which is opposite to the polarity of the magnet (s) on the opposite side of the staggered infeed path). The arrangement of the at least three magnets provides a predetermined change in the direction of the field as the lamellar magnetic or magnetizable pigment particles in the coating composition travel through the magnets (direction of travel: arrow). According to one embodiment, the second magnetic field generating device (x40) comprises a) a first magnet and a third magnet on the first side of the feed path and b) a second magnet between the first and third magnets on the second opposite side of the feed path, the first and third magnets have the same polarity, with the second magnet having complementary polarity with respect to the first and third magnets, and wherein the magnetic axis of each of said three magnets is substantially perpendicular to the substrate surface (x10). According to another embodiment, the second magnetic field generating device (x40) further comprises a fourth magnet on the same side of the feed path as the second magnet having a polarity of the second magnet and complementary to the polarity of the third magnet, the second magnet having complementary polarity with respect to the first and third magnets, and wherein the magnetic axis of each of said four magnets is substantially perpendicular to the surface of the substrate (x10). As described in document EP 2157141 A1, the device generating the magnetic field can be located either under the layer containing the lamellar magnetic or magnetizable pigment particles, or above and below the layer.

Biaxial orientation of the lamellar magnetic or magnetizable pigment particles can be accomplished by moving the substrate (x10) carrying the coating layer (x20) with the first magnetic field generating device (x30) mounted on the transfer device (TD) described herein, preferably on a Rotating Magnetic Cylinder (RMC) described herein at an acceptable speed close to a static second magnetic field generating device (x40) that is a Halbach array with linear permanent magnets or through an array of two or more Halbach arrays located in acceptable layout. Halbach linear permanent magnet assemblies consist of assemblies containing many magnets with different magnetization directions. A detailed description of Halbach's permanent magnets was given by Z.Q. Z.Q. Zhu et D. Howe (Halbach permanent magnet machines and applications: a review, IEE. Proc. Electric Power Appl. 2001, 148, pp. 299-308). The magnetic field produced by such a Halbach assembly with linear permanent magnets is such that it is concentrated on one side while attenuating to almost zero on the other side. Typically, Halbach linear permanent magnet assemblies contain one or more non-magnetic blocks made of, for example, wood or plastic, in particular a plastic known to have good self-lubricating properties and wear resistance, such as polyacetal (also called polyoxymethylene, POM ) resins, and magnets made of high coercive magnetic materials such as neodymium-iron-boron (NdFeB).

Biaxial orientation of the lamellar magnetic or magnetizable pigment particles can be accomplished by moving the substrate (x10) carrying the coating layer (x20) with the first magnetic field generating device (x30) mounted on the transfer device (TD) described herein, preferably on a rotating magnetic cylinder (RMC) described in this

- 17 038016 document, with an acceptable speed at close distance to a static second device (x40), generating a magnetic field, such as described in document EP 1519794 B1. Suitable devices include permanent magnets located on each side of the substrate (x10) carrying the coating layer (x20) on top of it, so that the magnetic field lines are substantially parallel to the surface of the substrate (x10). According to one embodiment, the second magnetic field generating device (x40) comprises one or more pairs of two dipole bar magnets, wherein the magnetic axis of each of said two dipole bar magnets is substantially parallel to the surface of the substrate (x10), and wherein the magnetic direction is the two bar dipole magnets are opposite. In another embodiment, and as depicted in FIG. 4A-B, the second magnetic field generating device (x40) comprises one or more pairs of two dipole bar magnets (x41a, x41b), wherein the magnetic axis of each of said two dipole bar magnets is substantially perpendicular to the substrate surface (x10), and the magnetic direction of the two bar dipole magnets is opposite. According to another embodiment, instead of containing one or more pairs of two dipole bar magnets, wherein the magnetic axis of each of said two dipole bar magnets is substantially perpendicular to the surface of the substrate (x10), and the magnetic direction of the two dipole bar magnets is opposite, the second the magnetic field generating device (x40) comprises a U-shaped magnet (also referred to in the art as a horseshoe magnet), the north and south poles of which are located in the same plane at the open end of the magnet. The U-shaped magnet can be a single piece, or it can be composed of two separate pieces, wherein said two separate pieces may be in direct contact or may be spaced apart and connected to each other by a non-magnetic base.

The second device (x40) generating the magnetic field can be contained in one or more holders (x42). One or more holders (x42) described herein are preferably made of one or more non-magnetic materials described herein for one or more holders, one or more plates, or one or more spacers (x31) described herein. ...

As described herein above, the thus oriented lamellar magnetic or magnetizable pigment particles are fixed / immobilized in their orientation and position (i.e., after solidification) to form an optical effect layer (OEL). As shown in FIG. 1A, the curing step described herein (step c)) is preferably carried out with a curing unit (x50), while the substrate (x10) supporting the coating layer (x20) described herein is still on top the first device (x30) generating a magnetic field, and while the substrate (x10) carrying the coating layer (x20) described in this document no longer moves close to the static second device (x40) generating a magnetic field, i.e. e. the step of providing solidification described herein is carried out partially simultaneously with step b) when the generated magnetic field (H3) generated by the first and second components of the magnetic field vector (i.e., obtained by adding the vectors H1 and H2) described in this document is greater than zero, preferably greater than 50 mT.

FIG. 4A-C schematically illustrate an embodiment of a method for orienting platy magnetic or magnetizable pigment particles contained in a coating layer (x20) on a substrate (x10) using a linear magnetic transfer device (LMTD) transfer device (TD) according to the present invention. Instead of installing the first magnetic field generating device (x30) on the magnetic rotating orientation cylinder (RMC), the said first magnetic field generating device (x30) is able to move (see arrow), for example, using a rail (x33), close to a static second device (x40) generating a magnetic field. As shown in FIG. 4A-C, the method described herein employs a mobile first magnetic field generating device (430) and a static second magnetic field generating device (440) such as those described herein.

In the embodiment shown in FIG. 4A-C, the first magnetic field generating device (430) consists of a bar-type dipole magnet, the magnetic axis of the south-north direction of which is substantially parallel to the surface of the substrate (410), while the north pole of which is directed towards the second device (440), generating a magnetic field, and the magnet is located in a non-magnetic holder (431). A non-magnetic holder (431) containing a first magnetic field generating device (430) is positioned over the support block (432) and the rail (433) to be movable.

In the embodiment shown in FIG. 4A-C, the second magnetic field generating device (440) consists of two bar dipole magnets (441a and 441b), with said two bar dipole magnets (441a and 441b) independently inserted into non-magnetic holders (442a and 442b) fixed in a non-magnetic frame (443), while the directions of the magnetic field south-north of these two bar dipole magnets (441a and 441b) are opposite to each other (the south pole of one bar dipole magnet (441a) is facing the surface of the substrate (410),

- 18 038016 and the north pole of the other magnet (441b) is facing the surface of the substrate (410)), while the magnetic south-north axis of each of these two bar dipole magnets (441a and 441b) is perpendicular to the surface of the substrate (410) (i.e. the magnetic axis of the south-north direction of which is substantially perpendicular to the magnetic axis of the south-north direction of the surface of the first device (430) generating a magnetic field), and wherein said two bar dipole magnets (441a and 441b) are spaced apart by a distance A1.

Preferably, the surface of the substrate (410) carrying the coating layer (420) is flush with the bottom surface of the two bar dipole magnets (441a and 441b). Preferably, the center of the coating layer (420) is located at the center of the first magnetic field generating device (430) and equidistant between the two bar dipole magnets (441a and 441b) of the second magnetic field generating device (440), i.e. at a distance of _1/2 A1 from each of the bar dipole magnets (441a and 441b).

As shown in FIG. 4A, the curing step described herein is preferably performed while the substrate (410) carrying the coating composition (420) described herein is still on top of the first magnetic field generating device (430), and how the substrate (410) and the first magnetic field generating device (430) move a distance (X) from the static second magnetic field generating device (440) in the direction of movement.

Each of the first device (x30), generating a magnetic field, and the second device (x40), generating a magnetic field, has a specific magnetic flux density component of the unit of Wb / m ² (Tesla), and the ratio of magnetic flux density of said first device (x30) generating a magnetic field and the magnetic flux density of said second magnetic field generating device (x40) is less than 4.0, preferably less than about 1.9, and more preferably from about 1.5 to about 0.5.

Magnetic flux densities can be measured by placing a Hall magnetometer (x60) connected to a gaussmeter in the same position as the substrate (x10), the carrier layer (x20) of the coating containing the lamellar magnetic or magnetizable pigment particles, during the method according to the present invention.

FIG. 5A-B are a schematic top view (FIG. 5A) and cross-section (FIG. 5B) of the first magnetic field generating device (530) shown in FIG. 4A-C, and a Hall magnetometer (560) used to measure the magnetic flux density of the first magnetic field generating device (530). FIG. 5C-D are schematic views of the top (FIG. 5C) and cross-section (FIG. 5D) of the first magnetic field generating device (530) shown in FIG. 4A-C, and a coating layer (520) on a substrate (510) to show that the Hall magnetometer (560) is located in the same position as the substrate (510) will be located, carrying a coating layer (520) containing plate magnetic or magnetizable pigment particles during the process according to the present invention. In the embodiment shown in FIG. 5, the first magnetic field generating device (530) consists of a bar-type dipole magnet, the magnetic axis of the south-north direction of which is substantially parallel to the surface of the substrate (510) in use, and which has a length (L2), a width (L1) and a thickness (L3). As illustrated in FIG. 5A-B, a Hall magnetometer (560) is located on top of the first magnetic field generating device (530), at a distance A2 from the upper surface of said first magnetic field generating device (530), with its center located in the center of the first device (530) generating a magnetic field relative to the length (L2) and width (L1). As illustrated in FIG. 5B, the location of the Hall magnetometer (560) corresponds to the location of the top surface of the substrate (510) carrying the coating layer (520) during the method of the present invention.

FIG. 6 schematically depicts a second magnetic field generating device (640) of FIG. 4A-C, and a Hall magnetometer (660) used to measure the magnetic flux density of the second magnetic field generating device (640). The second magnetic field generating device (640) consists of two bar dipole magnets (641a and 641b) spaced apart at a distance A1 and having a length (L4), a width (L5) and a thickness (L6). As illustrated in FIG. 6, the Hall magnetometer (660) is capable of moving (see arrow) a close distance to the second magnetic field generating device (640).

FIG. 6A-C schematically depict a second magnetic field generating device (640) of FIG. 4A-C, and a Hall magnetometer (660) used to measure the magnetic flux density of the second magnetic field generating device (640). As illustrated in FIG. 6A, the Hall magnetometer (660) is capable of moving (see arrow) close to the second magnetic field generating device (640).

FIG. 6A-C schematically illustrate a side view (FIG. 6A), a top view (FIG. 6B) and another side view (FIG. 6C) of a second magnetic field generating device (640) and a Hall magnetometer (660). The second magnetic field generating device (640) shown in FIG. 6A-C corresponds to the second magnetic field generating device (640) of FIG. 4A-B, i.e. contains two

- 19 038016 bar dipole magnets (641a and 641b) spaced apart (A1). FIG. 6A-C illustrate the position of the Hall magnetometer (660) used to measure the magnetic field of the second magnetic field generating device (640). As illustrated in FIG. 6A-C, the Hall magnetometer (660) moves between two dipole bar magnets (641a and 641b) of the second magnetic field generating device (540). The center of the Hall magnetometer (660) is located halfway (1/2 A1) from each dipole bar magnet (641a and 641b) and at the lower surface of the second magnetic field generating device (640) for measuring the magnetic field (H2). The location of the Hall magnetometer (660) corresponds to the location of the top surface of the substrate (610) carrying the coating layer (620) during the method of the present invention. The position and movement of the Hall magnetometer (660) along the second magnetic field generating device (640) corresponds to the position and movement of the coating layer containing magnetic or magnetizable pigment particles that are carried by the substrate during the orientation method of the present invention.

Preferably and as described hereinabove for FIG. 6A-C, for the substrate (610) flush with the bottom surface of the two bar dipole magnets (641a and 641b), the center of the Hall magnetometer (660) is flush with the bottom surface of the two bar dipole magnets (641a and 641b). Preferably and as described hereinabove for FIG. 6A-C for the center of the coating layer (620) equidistant between the two bar dipole magnets (641a and 641b) of the second magnetic field generating device (640), i.e. at a distance of _1/2 A1 from each of the bar dipole magnets (641a and 641b), the center of the Hall magnetometer (660) is equidistant between the two bar dipole magnets (641a and 641b) of the second magnetic field generating device (640), i.e. e. at a distance of _1/2 A1 from each of the bar dipole magnets (641a and 641b). The location of the Hall magnetometer (660) corresponds to the location of the top surface of the coating layer (620) that is carried by the substrate (610) during the method of the present invention.

The method described herein provides optical effect layers (OELs) exhibiting an eye-catching dynamic effect to provide, in combination, high resolution and high contrast.

A conoscopic reflectometer (obtained from Eckhartd Optics LLC, 5430 Jefferson Ct, White Bear Lake, MN 55110; http://eckop.com) was used to characterize the biaxial orientation of plated magnetic or magnetizable pigment particles and OEL brightness obtained by the method described in this document.

FIG. 7A schematically shows the principles of conoscopic reflectometry, which is based on the focal plane to focal plane principle (772-770), (where (770) is the front focal plane of the lens, which is located at a distance f from the lens; (772) is the back focal plane. the plane of the lens, which is located at a distance f from the lens) with image transformation (i.e., with a Fourier transform) using a lens or a lens system displaying the directions of the incoming rays (χ1, χ ₂ , χ ₃ ) in the anterior focal plane (770) lenses into spots (x1, x ₂ , x ₃ ) in the rear focal plane (772) of the lens. FIG. 7B is another illustration of the principle of conoscopic reflectometry as used in the present invention to measure the biaxial orientation of pigment particles and the brightness of the OEL. FIG. 7B schematically illustrates the complete configuration of a back-reflection conoscopic reflectometer, comprising a front optics (771) performing focal plane-to-focal plane imaging, a light source (780) and a translucent coupling mirror (790) for illumination through the optics of a small spot on the OEL. (720) on a substrate (710) with a parallel light beam (773) at orthogonal incidence, and a rear optics (795) containing a camera sensor (796) for capturing an image of a spot pattern present in the rear focal plane (772) of the front optics. It has been shown that two different orientations (721, 722) of lamellar magnetic or magnetizable pigment particles reflect back orthogonally the incident beam in two different directions of the beam, which are focused by the front optics into two separate spots x1 and x ₃ in its rear focal plane (772). The image locations of these spots are recorded by the rear optics (795) and the sensor (796) of the camera.

To measure the reflection characteristics, an OEL containing oriented lamellar magnetic or magnetizable pigment particles was evaluated every millimeter using a 1 mm diameter parallel light beam (LED, 520 nm) at orthogonal incidence, and the reflected light was imaged at each point. From these images, the corresponding distributions of the deflection angles (χ,) of the backscattered light spot were obtained by applying a 2-dimensional Gaussian distribution to the image data collected on the back focal plane of the conoscopic reflectometer at each location; meanwhile, the average (χ, Ψ) values correspond to the center of the Gaussian distribution.

Lamellar magnetic or magnetizable pigment particles within the beam diameter of the light

- 20 038016 shifts (773) reflect light back into the optics at deflection angles (χ, Ψ) in spherical polar coordinates. The angles of deflection of the reflected beam (χ, Ψ) of each pigment particle are translated by the lens (771) to the locations (X, Y) of the focal plane (772). If two pigment particles that are located at different locations within the pulse modulated beam (773) have the same orientation, the reflected light from the two pigments will hit the sensor surface at the same location (X, Y).

FIG. 8 is a schematic illustration of another example of measuring the orientation of the magnetic or magnetizable lamellar pigment particles forming the OEL and contained within the coating layer (820) using a conoscopic reflectometer containing an illumination source (880) and a focal plane (872). FIG. 8 OEL is illustrated as a cross-sectional view of a coating layer (820) showing the orientation of pigment particles following a convex curve along the X direction of the sensor. The orientation of the pigment particles in the pulsed modulated beam illumination spot (873), following a convex curve, is translated to a location (X, Y) in the focal plane (872) of the conoscopic reflectometer.

FIG. 9A-B schematically illustrate a spot of reflected light at the focal plane of an OEL conoscopic reflectometer containing pigment particles oriented according to the rolling band effect (as illustrated in FIG. 8). FIG. 9A illustrates an example of an OEL having a high degree of biaxial orientation, which results in little light scattering of the reflected illumination beam, i.e., a narrow distribution of the positions (X, Y) of the reflected illumination beam in the focal plane of the lens of the conoscopic reflectometer. Therefore, the spot of the reflected light beam will be relatively small for an OEL containing pigment particles having a high degree of biaxial orientation (Fig.9A), while the spot of a reflected light beam will be relatively large for an OEL containing pigment particles having a low degree of biaxial orientation ( as illustrated in Fig. 9B). In addition, the brightness of the spot of the reflected light beam is directly proportional to the degree of biaxial alignment of the pigment particles due to the focused reflected light beam in a relatively small spot. FIG. 9C-D schematically illustrate the Gaussian distribution of azimuth () of the reflected light beam according to FIG. 9A-B, respectively. As a result of the narrower distribution in FIG. 9C as compared to FIG. 9D the amplitude of the Gaussian function in FIG. 9C is larger than FIG. 9D. The amplitude of the Gaussian function is substantially proportional to the brightness of the spot of the reflected light beam. Thus, the measurement of the brightness of the spot of the reflected light beam reflects the degree of biaxial orientation of the lamellar magnetic or magnetizable particles of the OEL pigment. To compare the degree of orientation of several OELs, intensities are measured at equivalent locations at each OEL, that is, where the mean angles (χ, Ψ) are identical for different samples. For simplicity, the samples are preferably measured in the middle of the sample at locations where the mean angles of deflection (χ, Ψ) are perpendicular to the surface.

The present invention further provides printers and their applications for producing optical effect layers (OELs) described herein. The printing devices described herein comprise a transfer device (TD) described herein, preferably a rotating magnetic cylinder (RMC) described herein, and at least one of second devices (x40) generating a magnetic field, described herein, wherein the transfer device (TD) described herein, preferably the rotating magnetic cylinder (RMC) described herein, comprises at least one of the first magnetic field generating devices (x30) described in herein, wherein said at least one of the first magnetic field generating devices (x30) described herein is installed on said transfer device (TD) described herein. Preferably, the printing devices described herein comprise a rotating magnetic cylinder (RMC) described herein and at least one of the second magnetic field generating devices (x40) described herein, wherein the rotating magnetic cylinder ( RMC) described herein contains at least one of the first magnetic field generating devices (x30) described herein, wherein said at least one of the first magnetic field generating devices (x30) described herein the document is preferably mounted on the annular grooves or lateral grooves of a rotating magnetic cylinder (RMC). In an embodiment, the Rotary Magnetic Cylinder (RMC) is part of a rotary, sheet- or web-fed industrial printing press that operates continuously at high print speeds.

It is understood that a transfer device (TD), preferably a rotating magnetic cylinder (RMC), comprising at least one of the first magnetic field generating devices (x 30) mounted thereon, as well as at least one of the second devices (x40 ) generating a magnetic field described in this document is used in part or in combination with a part, or it is a part of equipment for printing or coating. In an embodiment 21 038016, the transfer device (TD) is a rotating magnetic cylinder (RMC) such as described herein, said rotating magnetic cylinder (RMC) preferably being part of a rotary, industrial sheet-fed press. or a web that runs continuously at high print speeds.

Printing devices comprising a transfer device (TD) described herein, preferably a rotating magnetic cylinder (RMC) described herein, comprising at least one of the first magnetic field generating devices (x30) described herein, and at least one of the second magnetic field generating devices (x40) described herein may comprise a mechanism for supplying a substrate, such as described herein, coated with a layer of plate-like magnetic or magnetizable pigment particles described herein, so that the first device (x30) generating a magnetic field and the second first device (x40) generating a magnetic field generate the generated magnetic field, which acts on the pigment particles to orient them to form an optical effect layer (OEL). In an embodiment of printers comprising a transfer device (TD) described herein, preferably a rotatable magnetic cylinder (RMC) described herein, the substrate is fed by a mechanism to feed the substrate in the form of sheets or web.

Printing devices comprising a transfer device (TD) described herein, preferably a rotating magnetic cylinder (RMC) described herein, comprising at least one of the first magnetic field generating devices (x30) described herein, and at least one of the second magnetic field generating devices (x40) described herein may comprise a system for guiding a substrate. In the context of this document, the term substrate guiding system refers to an apparatus that holds a substrate (x10), a carrier (x10) coating layer, in close contact with a transfer device (TD) described herein, preferably a rotating magnetic cylinder (RMC) described in this document, and the first devices (x30) that generate a magnetic field. The system for guiding the substrate can be a grabber and / or a vacuum system. In particular, the gripper can serve to hold the leading edge of the substrate (x10) and transfer it (x10) from one part of the printing press to the next, and the vacuum system can serve to push the surface of the substrate (x10) to the surface of the transfer device (TD ) described herein, preferably the Rotating Magnetic Cylinder (RMC) described herein, and the first magnetic field generating devices (x30) and keep it rigidly aligned. The system for guiding the substrate may comprise, in addition to or instead of the gripper and / or the vacuum system, other pieces of equipment for guiding the substrate, including, but not limited to, a roller or set of rollers, a brush or set of brushes, a tape and / or a set of tapes, a blade or a set. blades, or a spring or a set of springs.

Printing devices comprising a transfer device (TD) described herein, preferably a rotating magnetic cylinder (RMC) described herein, comprising at least one of the first magnetic field generating devices (x30) described herein, and at least one of the second magnetic field generating devices (x40) described herein may comprise a coating or printing unit for applying a coating composition comprising the lamellar magnetic or magnetizable pigment particles described herein onto the substrate (x10) described herein to form the coating layer (x20) described herein.

Printing devices comprising a transfer device (TD) described herein, preferably a rotating magnetic cylinder (RMC) described herein, comprising at least one of the first magnetic field generating devices (x30) described herein, as well as at least one of the second devices (x40) generating a magnetic field described herein may comprise a curing unit (x50), preferably a curing unit, for at least partially curing the coating layer (x20) containing the lamellar magnetic or magnetizable pigment particles that were magnetically oriented by the resulting magnetic field generated by the first and second magnetic field vector components of the first and second magnetic field generating devices (x30 and x40) described herein, thereby fixing the orientation and position of the magnetic or magnetizable pigment particles to obtain a layer with opt oelectrical effect (OEL).

The present invention provides the methods described herein and the printing devices described herein for producing an optical effect layer (OEL) on the substrate (x10) described herein. The substrate (x10) described herein is preferably selected from the group consisting of papers or other fibrous materials (including woven and non-woven fibrous materials) such as cellulose, paper-containing materials, glasses, metals, ceramics, plastics and polymers, metallized plastics or polymers, composites and mixtures, or combinations of two or more of them. Typical paper,

- 22 038016 paper-like or other fibrous materials are made from a wide variety of fibers, including but not limited to manila hemp, cotton fiber, linen fiber, wood pulp, and mixtures thereof. As is well known to those skilled in the art, cotton fiber and cotton / linen fiber blends are preferred for banknotes, while wood pulp is typically used for security documents other than banknotes. Typical examples of plastics and polymers include polyolefins such as polyethylene (PE) and polypropylene (PP), including biaxially oriented polypropylene (BOPP), polyamides, polyesters such as poly (ethylene terephthalate) (PET), poly (1,4-butylene terephthalate) (PBT), poly (ethylene-2,6-naphthoate) (PEN) and polyvinyl chloride (PVC). High velocity air jet spun olefin fibers such as those sold under the trademark Tyvek® can also be used as support. Typical examples of metallized plastics or polymers include the plastics or polymeric materials described herein above, on the surface of which metal is disposed continuously or discontinuously. Typical examples of metals include, but are not limited to, aluminum (Al), chromium (Cr), copper (Cu), gold (Au), silver (Ag), alloys thereof, and combinations of two or more of the aforementioned metals. The metallization of the plastic or polymeric materials described herein above can be accomplished by an electrodeposition process, a high vacuum coating process, or by a spray process. Typical examples of composites include, without limitation, multilayer structures or laminates of paper and at least one plastic or polymer material, such as described herein above, as well as plastic and / or polymer fibers included in a paper-like or fibrous material, such as described in this document above. Of course, the substrate may contain additional additives known to those skilled in the art, such as fillers, sizing agents, brighteners, processing aids, reinforcing or wetting agents, etc. When OELs obtained according to the present invention are used for decorative or cosmetic purposes, including, for example, nail varnishes, said OEL can be obtained on other types of substrates, including nails, artificial nails, or other parts of an animal or human.

If the OEL obtained according to the present invention is on the security document, and also in order to further increase the level of security and protection against counterfeiting and illegal reproduction of the specified security document, the substrate may contain printed, coated, or laser-marked or laser-punched marks, watermarks , security threads, fibers, confetti, luminescent compounds, windows, foils, decals, and combinations of two or more of them. For the same purpose of further increasing the level of security and protection against counterfeiting and illegal reproduction of the protected documents, the substrate may contain one or more marker substances or markers and / or machine-readable substances (for example, luminescent substances, substances absorbing in the UV / visible / IR ranges, magnetic substances and their combinations).

If necessary, a primer coat can be applied to the substrate prior to step a). This can improve the quality of the optical effect layer (OEL) described herein, or promote adhesion. Examples of these primer layers can be found in WO 2010/058026 A2.

In order to increase durability by increasing the resistance to dirt or chemical resistance and cleanliness, and thus the service life of an article, security document or decorative element or object containing an optical effect layer (OEL) obtained by the method described in this document, or with In order to alter their aesthetic appearance (eg, optical gloss), one or more protective layers can be applied over the optical effect layer (OEL). If present, one or more protective layers are usually made of protective varnishes. The protective varnishes can be radiation curable compositions, heat curing compositions, or any combination thereof. Preferably, the one or more protective layers are radiation curable compositions, more preferably UV and visible radiation curable compositions. Protective layers are usually applied after the formation of an optical effect layer (OEL).

The present invention further provides optical effect layers (OEL) obtained by the method described herein and / or using the printing device described herein.

The optical effect layer (OEL) described herein can be applied directly to a substrate on which it must remain permanently (eg, for banknote applications). Alternatively, for industrial purposes, an optical effect layer (OEL) can also be applied to a temporary substrate from which the OEL is subsequently removed. This can, for example, facilitate the production of an optical effect layer (OEL), in particular while the binder is still in its liquid state. Then, after the coating composition has cured for making an optical effect layer (OEL), the temporary OEL substrate can be removed.

Alternatively, in another embodiment, an adhesive layer may be present on

- 23 038016 an optical effect layer (OEL) or may be present on a substrate containing the OEL, said adhesive layer being located on the side of the substrate opposite to the side to which the OEL is applied, or on the same side as the OEL and over OEL. Thus, the adhesive layer can be applied to an optical effect layer (OEL) or to a substrate, said adhesive layer preferably being applied after completion of the curing step. Such a product can be attached to all types of documents or other products or objects without printing or other processes involving machines and mechanisms and rather high labor costs. Alternatively, the substrate described herein containing the optical effect layer (OEL) described herein can be in the form of a transfer foil that can be applied to a document or article in a separate transfer step. To this end, the substrate is provided with a release coating on which an optical effect layer (OEL) is produced as described herein. One or more adhesive layers can be applied over the optical effect layer (OEL) thus obtained.

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

This document also describes articles, in particular security documents, decorative elements or objects containing an optical effect layer (OEL) obtained according to the present invention. Articles, in particular security documents, decorative elements or objects, may contain more than one (eg, two, three, etc.) OELs obtained according to the present invention.

As mentioned herein above, the optical effect layer (OEL) obtained according to the present invention can be used for decorative purposes, as well as for the security and authentication of a security document.

Typical examples of decorative elements or objects include, but are not limited to, luxury goods, cosmetic packaging, automotive parts, electronic / electrical appliances, furniture, and nail products.

Protected documents include, but are not limited to, valuable documents and valuable commercial goods. Typical examples of valuable documents include, but are not limited to, banknotes, legal documents, tickets, checks, vouchers, tax and excise stamps, agreements and the like, identification documents such as passports, identity cards, visas, driver's licenses, bank cards , credit cards, transaction cards, documents or access cards, admission tickets, tickets for public transport, high school diplomas or academic degrees, etc., preferably banknotes, identity documents, licensing documents, driver's IDs and credit cards. The term valuable commercial product refers to packaging materials, in particular for cosmetic products, nutraceutical products, pharmaceutical products, spirits, tobacco products, beverages or food products, electrical / electronic products, textiles or jewelry, i.e. products that must be protected from counterfeiting and / or illegal reproduction, in order to guarantee the authenticity of the contents of the package, similar, for example, to genuine medicines. Examples of these packaging materials include, but are not limited to, labels such as trademark authentication labels, tamper evident labels, and seals. It should be noted that the disclosed substrates, valuable documents and valuable commercial goods are given by way of example only, without limiting the scope of the present invention.

Alternatively, an optical effect layer (OEL) can be applied to an auxiliary substrate such as, for example, a security thread, security strip, foil, decal, window or label, and then transferred to the security document in a separate step.

One skilled in the art can make a number of changes within the spirit of the present invention in the specific embodiments described above. These changes are within the scope of the present invention.

In addition, all documents that are referenced throughout the text of this description are hereby fully incorporated into the present description, as if they were fully set forth therein.

Examples of

The examples were carried out using a UV-curable screen printing ink according to the formula shown in table. 1, and the first and second magnetic field generating devices described later herein.

- 24 038016

Table 1

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

(*) 7-layer plate-like optically variable magnetic pigment particles with a color change from gold to green, in the form of flakes with a diameter of _{approximately 9.3 microns d 50} and a thickness of approximately 1 micron, obtained from JDSUniphase, Santa Rosa, CA.

First Magnetic Field Generating Device (FIGS. 4A-C, not to scale)

A rod dipole magnet (430) made of NdFeB N40 was used as the first magnetic field generating device. The rod dipole magnet (430) had the following dimensions: 30 mm (L1) x 18 mm (L2) x 6 mm (L3). As shown in FIG. 4B-C, a bar dipole magnet (430) was embedded in a non-magnetic holder (431) made of high density polyethylene (HDPE) and had the following dimensions: 40 mm (L7) x 40 mm (L8) x 25 mm (L9) ... The top surface of the dipole bar magnet (430) was located at a distance (A2) of approximately 15 mm from the top surface of the non-magnetic holder (431).

As shown in FIG. 4B-C, a bar dipole magnet (430) embedded in a non-magnetic holder (431) was able to travel close to the static second device (440) generating a magnetic field (i.e., through the magnetic field of the second device (440), generating a magnetic field), using a support block (432) and a rail (433), while the specified rail (433) was fixed in the frame (443).

The rail (433) (from ThorLabs) was made of anodized aluminum and had the following dimensions: 448 mm (L13) x 40 mm (L14) x 10 mm (L15).

The support block (432) contained the first part (432a), the second part (432b). The first piece (432a) was made of anodized aluminum (Aluminum Breadoard from ThorLabs) and was 112mm (L16) x 65mm (L17) x 13mm (L18) and was glued to the top of the second piece (432b ). The second part (432b) was made of high density polyethylene (HDPE), had the following dimensions: 112 mm (L16) x 65 mm (L17) x 37 mm (L19), and contained a recess suitable for placing the second part (432b) on rail (433) and having the following dimensions: 65 mm (L17) x 40 mm (L14) x 5 mm (L20).

A support block (432), made of two parts (432a-b), was located on the rail (433) so that it could be moved by sliding on the specified rail (433) along its length (see Fig. 4A).

Second Magnetic Field Generating Device (FIGS. 4A-4B, not to scale)

A pair of two bar dipole magnets (441a and 441b) was used as the second magnetic field generating device (440). Each of the two bar dipole magnets (441a and 441b) had the following dimensions: 48mm (L4) x 24mm (L5) x 10mm (L6) and was made from NdFeB N40. The magnetic axis of each of the two bar dipole magnets (441a and 441b) was substantially parallel to the length (L4) of said magnets (i.e., substantially perpendicular to the surface of the substrate (410)), the magnetic direction of the first of said two bar dipole magnets (441a) was opposite to the magnetic direction of the second of these two bar dipole magnets (441b). Two dipole bar magnets (441a and 441b) were spaced (A1 = 48 mm) apart and were independently embedded in a pair of non-magnetic holder (442a and 442b) made of polyoxymethylene (POM).

As shown in FIG. 4B, the non-magnetic holder pair comprised two blocks (442a and 442b), each

- 25 038016 of which had the following dimensions: 52 mm (L10) x 30 mm (L11) x 12 mm (L12), and each of which contained a recess for the independent insertion of two bar dipole magnets (441a and 441b). Each of the two bar dipole magnets (441a and 441b) was located at a distance (A3) of approximately 1 mm from the surface of its respective non-magnetic holder (442a and 442b) facing the other bar dipole magnet, and at a distance (A4) of approximately 2 mm from the bottom surface of its corresponding non-magnetic holder (442a and 442b).

As shown in FIG. 4B, two non-magnetic holders (442a and 442b) are connected to each other by an anodized aluminum frame (443) containing two mounting plates (443a and 443c) of a frame (Aluminum Breadboard from Thorlabs Inc.) and a frame post (443b), made of anodized aluminum (Large Right Angle Bracket AP90 / RL from Thorlabs Inc.).

The frame mounting plate (443a) was 450mm (L21) x 300mm (L22) x 13mm (L23). The rack (443b) of the frame had the following dimensions: 176 mm (L24) x 125 mm (L26) x 30 mm (L25). The frame mounting plate (443c) was 385mm (L28) x 100mm (L27) x 13mm (L23).

Frame (443) contained three rectangular plates (443d) having the following dimensions: 64mm (L29) x 8mm (L30) x 75mm (L31) x 8mm (L32) x 8mm (L33) x 70mm (L34 ) x 34 mm (L35).

Samples 1-1 - 1-4 (Fig. 4)

Square samples of 25 mm x 25 mm were independently printed on a black paper substrate (Gascogne Laminates M-cote 120) (410) using UV-curable screen printing ink from Table. 1 with a laboratory screen printer using a T90 screen to form a coating layer (420) of approximately 20 μm thickness.

While the coating layer (420) was still in a wet and not yet cured state, the substrate (410) was placed on top of the first device (430), generating a magnetic field, in particular over the non-magnetic holder (431), while the center of the said layer (420) the coatings were placed in the center of the first magnetic field generating device (430). The substrate (410) carrying the coating layer (420) was placed at a distance (A2) of about 2 to about 15 mm (values given in Table 2) from the top surface of said first magnetic field generating device (430), i.e. e. the substrate (410) was placed in direct contact with the holder (431) to form an assembly. The magnetic axis of the bar dipole magnet of said first magnetic field generating device (430) was substantially parallel to the surface of the substrate (410), with the north pole pointing in a direction substantially perpendicular to the two opposite magnetic axes of the bar magnets (441a, 441b) of the second device (440) generating a magnetic field.

As shown in FIG. 4A and with the help of the support block (432) and the track (433), the substrate (410), the carrier layer (420) of the coating, and the non-magnetic holder (431) containing the first device (430), generating a magnetic field, were simultaneously moved back and forth eight times with a linear velocity of approximately 10 cm / s at close range to the second device (440) generating a magnetic field. The substrate (410) carrying the coating layer (420) and the holder (431) containing the first magnetic field generating device (430) were simultaneously moved close to the second magnetic field generating device (440), the center of the first device (430 ), the magnetic field generating (also corresponding to the center layer (420) coating, i.e., center of feature in a strip rolling over) was located at a distance _^(1/2 A1) about 25 mm from each of the core dipole magnets (441a and 441b) and the surface of the substrate (410) was flush with the bottom surface of the dipole bar magnets (441a and 441b). The magnetic axis of each of the two dipole bar magnets (441a and 44ab) of said second magnetic field generating device (440) was substantially perpendicular to the surface of the substrate (410), and the magnetic directions of the two dipole bar magnets (441a and 441b) were opposite, i.e. .e. the south pole of one of said two bar dipole magnets (441a) was pointing towards the surface of the substrate (410) and the north pole of the other magnet (441b) was pointing towards the surface of the substrate (410).

While the substrate (410) carrying the coating layer (420) was still in contact with the non-magnetic carrier (431) containing the first device (430) generating a magnetic field, and while the substrate (410) carrying the coating layer (420), and a non-magnetic holder (431) containing the first magnetic field generating device (430) were simultaneously moved at a distance (X) of approximately 50 mm from the second magnetic field generating device (440) in the direction of movement (indicated by the arrow in FIG.4A) , the coating layer (420) was hardened by exposure for about 0.5 s to a UV LED lamp (450) from Phoseon (FireFlex type 50 x 75 mm, 395 nm, 8 W / cm ² ) located at a distance of about 30 mm from the top surface of the substrate (410) carrying the coating layer (420) to form an OEL.

Samples 2-1 - 2-4

Comparative samples 2-1 - 2.4 were independently obtained according to the general procedure from document

- 26 038016 prior art WO 2015/086257 A1, including the following steps:

step i): A 25 mm x 25 mm square sample was printed on a black paper backing (Gascogne Laminates M-cote 120) using UV-curable screen printing ink from table. 1 with a laboratory screen printer using a T90 screen to form a coating layer approximately 20 μm thick;

step ii): while the coating layer was still wet and not yet cured, the substrate was placed on top of the non-magnetic holder described for samples 1-1 to 1-4, but without using the first device generating a magnetic field, with the center of said layer (420) the coatings were placed in the center of the non-magnetic holder. Using the support block (432) and track (433) described herein above, the coating layer was exposed to the magnetic field of the second magnetic field generating device described herein above and moved close to the second magnetic generating device. field described for samples 1-1 through 1-4 back and forth eight times at a linear velocity of approximately 10 cm / s, with the center of the non-magnetic holder positioned approximately 24 mm from each of the bar dipole magnets, and the lowest surface of the substrate placed flush with the bottom surface of the dipole bar magnets; and step iii): the substrate carrying the coating layer is removed from the magnetic field of the second magnetic field generating device and exposed to the magnetic field of the first magnetic field generating device described herein above. The substrate carrying the coating layer was placed at a distance (A2) of about 2 to about 15 mm (values given in Table 2) from the top surface of said first magnetic field generating device.

step iv): partly simultaneously with step iii) allowing the coating layer to cure by exposing for approximately 0.5 s to a UV LED lamp from Phoseon (type FireFlex 50 x 75 mm, 395 nm, 8 W / cm ² ) located on a distance of approximately 30 mm from the top surface of the substrate carrying the coating layer to form an OEL.

Measurement of magnetic flux densities of the first and second magnetic field generating devices (FIGS. 5A-B and 6A-C)

The magnetic flux density (mT, milli-Tesla) of the first devices (530) generating a magnetic field, samples 1-1-1-4 and samples 2-1-2-4 were independently measured by placing a Hall magnetometer (560) (Hirst Magnetic Instruments Ltd, TP002 transverse magnetometer) connected to a GM-08 gaussmeter (Hirst Magnetic Instruments Ltd), at a distance (A2) of about 2 to about 15 mm (values given in Table 2) from the top surface of the first device (530), generating a magnetic field, the center of which is located in the center of the first device (530), generating a magnetic field, relative to the length (L2) and width (L1).

The magnetic flux density (mT, milli-Tesla) of the second devices (640) generating the magnetic field, samples 1-1-1-4 and samples 2-1-2.4 were independently measured by moving the Hall magnetometer (660) along the device (640), generating a magnetic field, at a distance of _1/2 A1 (i.e. 24 mm) from each dipole bar magnet (641a and 641b) of the device (640) generating a magnetic field. The center of the Hall magnetometer (660) was flush with the bottom surface of the two bar dipole magnets (641a and 641b). The maximum magnetic flux density was measured at the center of the second magnetic field generating devices (640), along the travel path (see arrow in FIG. 6), at a distance of _1/2 L5 (from each of the dipole bar magnets (641a and 641b).

The ratio of the maximum magnetic flux density of the first device (x30) generating a magnetic field along the path of the sample and the magnetic flux density of the second device (x40) generating a magnetic field was calculated by dividing the measured values given in table. 2.

OEL brightness measurement of samples 1-1 - 1-4 and samples 2-1 - 2-4

The OEL brightness of samples 1-1 to 1-4 and samples 2-1 to 2-4 was independently measured by conoscopic reflectometry using a conoscopic reflectometer from Eckhartd Optics LLC (Eckhardt Optics LLC, 5430 Jefferson Ct, White Bear Lake, MN 55110; http://eckop.com).

Substrates (x10) bearing the (x20) coating layer were independently placed on a handheld coordinate plotter in the front focal plane of the conoscopic reflectometer. The dimensions of the coordinate plotter were adjusted in the range from 0 to 26 mm along both axes. The coordinate plotter carrying the substrate (x10) with the OEL was manually adjusted under the optical system so that the center of the printable area was facing the center of the optical system.

The (x20) coating layer containing the oriented pigment flakes was illuminated in the center of the OEL with a highly directional parallel green light beam (520 nm) with a diameter of approximately 1 mm and measured every millimeter until the center of the sample was found and located under the indicated light beam. ...

Lamellar optically variable magnetic pigment particles in the diameter of the illumination beam reflected light back into the focal plane of the lens of the conoscopic reflectometer at deflection angles (χ, Ψ). The values obtained for the deflection angles (χ, Ψ) were averaged by applying the 2-27 038016 dimensional Gaussian function. Measurement of the amplitude of the Gaussian function of the deflection angles (χ, Ψ) gave the value of the brightness of the sample in the center of the OEL. Each sample was measured four times, and the average brightness values are given in table. 2.

The brightness measurement reflects the degree of biaxial orientation of the lamellar optically variable magnetic pigment particles: the higher the value, the better the biaxial alignment. The brightness values of samples 1-1 - 1-4 and samples 2-1 - 2-4 are given in table. 2.

table 2

A2 [mm] magnetic density flow first device magnetic flux density of the second device (x40), generating ratio Brightness [optical unit] (xZO) generating a magnetic field [mT] magnetic field [mT] 1-1 fifteen 24 ^a) 46 ^a) 0.52 62 2-1 fifteen 24 ^a) 46 ^a ) 0.52 47 1-2 eleven 46 ^a ) 46 ^a ) 1.0 49 2-2 eleven 46 ^a ) 46 ^a ) 1.0 40 1-3 6 88 ^a) 46 ^a ) 1.91 37 2-3 6 88 ^a) 46 ^a ) 1.91 43 1-4 2 160 ^b) 46 ^a ) 3.48 39 2-4 2 160 ^b) 46 ^a ) 3.48 41

a) ± 3 mT; uncertainty due to the position of the Hall magnetometer

b) ± 5 mT; uncertainty due to the position of the Hall magnetometer

As shown in table. 2, the use of the first and second magnetic field generating devices with an H1 / H2 ratio of less than or equal to about 1.0 (i.e. samples 1-1 and 1-2) resulted in an OEL exhibiting significantly higher brightness. than the samples obtained according to the prior art (samples 2-1 and 2-2). The use of the first and second magnetic field generating devices with an H1 / H2 ratio greater than or equal to 1.9 and less than or equal to 3.48 yielded an OEL exhibiting similar brightness to prior art comparative samples (see samples 1-3 and 1-4 versus samples 2-3 and 2-4).

The method according to the present invention, which uses the first and second magnetic field generating devices described herein, allows the production of optical effect layers (OEL) in a mechanically reliable, easy-to-implement manner with industrial high-speed printing equipment, and allows Produce Optical Effect Layers (OEL) that not only show an eye-catching dynamic effect, but also high resolution and high contrast.

Claims (12)

CLAIM 1. A method for producing an optical effect layer (OEL) on a substrate (x10), characterized in that said method comprises the steps: a) applying to the surface of a substrate (x10) a coating composition containing lamellar magnetic or magnetizable pigment particles to form a coating layer (x20) on said substrate (x10), said coating composition being in the first state, b) placing a substrate (x10) carrying a coating layer (x20) on a first magnetic field generating device (x30) providing a first magnetic field vector component, said first magnetic field generating device (x30) being installed on a device for transfer (TD), thereby subjecting the platy magnetic or magnetizable pigment particles to the specified first component of the magnetic field vector, while moving the specified substrate (x10), the carrier layer (x20) of the coating, and the specified first device (x30), generating a magnetic field, on close distance to static second - 28 038016 to a device (x40) generating a magnetic field, wherein said second device (x40) generating a magnetic field provides a second component of the magnetic field vector, thereby exposing the lamellar magnetic or magnetizable pigment particles to the time-dependent magnetic field generated by the first and second components of the magnetic field vector, with biaxial orientation of at least part of the lamellar magnetic or magnetizable pigment particles, while the ratio of the magnetic flux density of the first device (x30), generating a magnetic field, and the magnetic flux density of the second device (x40), generating a magnetic margin is less than about 4.0; and c) allowing the coating composition to cure in the second state, fixing the lamellar magnetic or magnetizable pigment particles in their positions and orientations. 2. The method of claim 1, wherein the transfer device (TD) is a rotating magnetic cylinder (RMC). 3. A method according to claim 1 or 2, characterized in that the step of applying the coating composition to the substrate (x10) is performed by a printing process selected from the group consisting of gravure printing, screen printing, rotogravure printing and flexographic printing. 4. A method according to any of the preceding claims, characterized in that the coating composition is a UV and visible light curable composition and the step of providing curing is carried out by UV and visible light curing. 5. A method according to any of the preceding claims, characterized in that step c) of causing the coating composition to harden is carried out partially simultaneously with step b). 6. A method according to any of the preceding claims, characterized in that the first magnetic field generating device (x30) is selected from the group consisting of dipole magnets, quadrupole magnets, and combinations thereof. 7. A method according to any of the preceding claims, characterized in that the second device (x40) generating a magnetic field comprises a) a linear arrangement of at least three magnets that are staggered, wherein the magnetic axis of each of said three magnets substantially perpendicular to the surface of the substrate (x10), and wherein said at least three magnets on one side of the feed path have the same polarity, which is opposite to the polarity of the magnet (s) on the opposite side of the feed path, b) Halbach assembly with linear permanent magnets, with ) one or more pairs of two bar dipole magnets, wherein the magnetic axis of each of said two bar dipole magnets is substantially parallel to the surface of the substrate (x10), and wherein the magnetic direction of the two bar dipole magnets is opposite, d) one or more pairs of two bar dipole magnets (x41a, x41b), while the magnetic axis of each of these two with of the rod dipole magnets is substantially perpendicular to the surface of the substrate (x10) and the magnetic direction of the two rod dipole magnets is opposite, or e) a U-shaped magnet. 8. A method according to any of the preceding claims, characterized in that the lamellar magnetic or magnetizable pigment particles are lamellar optically variable magnetic or magnetizable pigment particles selected from the group consisting of lamellar magnetic thin film interference pigment particles, lamellar magnetic cholesteric liquid crystal pigment particles, lamellar interference coated pigment particles containing magnetic material and mixtures of two or more of them. 9. A method according to any of the preceding claims, characterized in that the substrate is selected from the group consisting of types of paper or other fibrous materials, materials containing paper, glasses, metals, types of ceramics, plastics and polymers, metallized plastics or polymers, composite materials and mixtures or combinations thereof. 10. A printing device for implementing the method according to claim 1 and comprising a transfer device (TD) on which a first device (x30) is installed, generating a magnetic field, providing a first component of a magnetic field vector, and a static second device (x40), generating a magnetic field providing the second component of the magnetic field vector, wherein said transfer device (TD) is a rotating magnetic cylinder (RMC), wherein the ratio of the magnetic flux density of the first magnetic field generating device (x30) and the magnetic flux density of the second the magnetic field generating device (x40) is less than about 4.0, the first magnetic field generating device (x30) being selected from the group consisting of dipole magnets, quadrupole magnets, and combinations thereof, and the second device (x40), generating a magnetic field, contains a) a linear arrangement of at least three magnets, which are located are staggered, with the magnetic axis of each of said three magnets being substantially perpendicular to the surface of the substrate (x10), and wherein said at least three magnets on one side of the feed path have the same polarity, - 29 038016 which is opposite to the polarity of the magnet (s) on the opposite side of the feed path, b) Halbach assembly with linear permanent magnets, c) one or more pairs of two bar dipole magnets, wherein the magnetic axis of each of said two bar dipole magnets is essentially parallel to the surface of the substrate (x10), and wherein the magnetic direction of the two bar dipole magnets is opposite, d) one or more pairs of two bar dipole magnets (x41a, x41b), wherein the magnetic axis of each of said two bar dipole magnets is substantially perpendicular the surface of the substrate (x10), and the magnetic direction of the two bar dipole magnets is opposite, or e) a U-shaped magnet. 11. The printing apparatus of claim 10, further comprising a system for guiding the substrate. 12. A method of applying a layer with an optical effect to a security document or decorative element, characterized in that an optical effect layer is formed on the security document or decorative element in accordance with the method according to any one of claims 1 to 9, so that it is a part of the protected document or decorative element.