UV-VIS radiation curable coating composition comprising magnetic or magnetizable pigment particles and method for producing optical effect layer

Abstract

The present invention relates to a UV-Vis radiation curable coating composition comprising magnetic or magnetisable pigment particles, as well as to a method for producing an optical effect layer (OEL) comprising magnetically oriented magnetic or magnetisable pigment particles, and to the use of said OEL as anti-counterfeiting means and decorative purposes on security documents or security articles. A UV-Vis radiation curable coating composition includes one or more (meth) acrylate monomers, one or more cyclic ether compounds, one or more vinyl ether compounds, one or more photoinitiators, one or more thermoplastic polymers, and non-spherical magnetic or magnetisable pigment particles.

Description

Technical Field

[0001] This invention relates to the following fields: UV-Vis radiation-curable coating compositions comprising magnetic or magnetizable pigment particles, methods for producing optical effect layers (OELs) comprising magnetically oriented magnetic or magnetizable pigment particles, and the use of said OELs as anti-counterfeiting means and decorative purposes on secure documents or security articles. Background Technology

[0002] It is known in the art to use inks, compositions, coatings, or layers containing oriented magnetic or magnetizable pigment particles, and in particular optically variable magnetic or magnetizable pigment particles, to generate security elements, for example, in the field of secure documents. Coatings or layers containing oriented magnetic or magnetizable pigment particles are disclosed, for example, in US 2,570,856; US 3,676,273; US 3,791,864; US 5,630,877 and US 5,364,689. Coatings or layers containing oriented magnetic color-shifting pigment particles are disclosed in WO 2002 / 090002 A2 and WO 2005 / 002866 A1, resulting in particularly attractive optical effects that can be used to protect secure documents.

[0003] For example, security features used in secure documents can generally be categorized into "covert" security features on one hand, and "overt" security features on the other. The protection provided by covert security features relies on the principle that the feature is difficult to detect, typically requiring specialized equipment and knowledge for detection. Overt security features, on the other hand, rely on concepts that can be easily detected with unassisted human senses; for example, the feature may be visible and / or detectable via tactile senses, while still being difficult to produce and / or replicate. However, the effectiveness of overt security features largely depends on their ease of identification as security features.

[0004] Magnetic or magnetizable pigment particles in printing inks or coatings allow for the induction of localized orientation of these particles in an uncured (i.e., wet) coating by applying a correspondingly structured magnetic field, followed by curing the coating, to produce magnetically induced images, designs, and / or patterns. The result is a fixed and stable magnetically induced image, design, or pattern. Materials and techniques for orienting magnetic or magnetizable pigment particles in coating compositions have been disclosed, for example, in US 2,418,479; US 2,570,856; US 3,791,864; DE 2006848-A; US 3,676,273; US 5,364,689; US 6,103,361; EP 0 406 667 B1; US ​​2002 / 0160194; US 2004 / 0009309; EP 0 710 508 A1; WO2002 / 09002 A2; WO 2003 / 000801 A2; WO 2005 / 002866 A1; WO 2006 / 061301 A1. In this way, highly counterfeit-resistant magnetically induced patterns can be produced. The safety elements discussed can only be generated by simultaneously utilizing magnetic or magnetizable pigment particles or corresponding inks, as well as specific techniques for printing the inks and orienting the pigments in the printed inks.

[0005] However, there is still a need for methods of producing UV-Vis radiation-curable coating compositions containing magnetic or magnetizable pigment particles and generating optical effect layers that exhibit striking effects and are mechanically robust. Summary of the Invention

[0006] Therefore, the object of the present invention is to overcome the deficiencies of the prior art. This is achieved by providing a UV-Vis radiation-curable coating composition comprising the following:

[0007] i) One or more (meth)acrylate oligomers, the total amount of which is between about 0 wt.% and about 10 wt.%, preferably between about 1 wt.% and about 10 wt.%;

[0008] ii) one or more (meth)acrylate monomers, preferably selected from the group consisting of tri(meth)acrylate, tetra(meth)acrylate and mixtures thereof, in total amount between about 1 wt.% and about 20 wt.%, wherein said monomer is different from the (meth)acrylate oligomer of i);

[0009] iii) One or more cyclic ether compounds, preferably selected from the group consisting of epoxides, oxetanes and mixtures thereof, more preferably alicyclic epoxides, oxetanes and mixtures thereof, in total amount between about 5 wt.% and about 40 wt.%;

[0010] iv) One or more vinyl ether compounds, in total amounts between about 10 wt.% and about 50 wt.%;

[0011] v) One or more onium photoinitiators, in total amounts between about 0.1 wt.% and about 10 wt.%;

[0012] vi) One or more photoinitiators selected from the group consisting of: alkoxyketones, acetophenones, benzophenones, ketone sulfones, benzyl ketal, benzoyl ether, phosphine oxides, phenyl glyoxylates, coumarins, camphorquinones, and mixtures thereof, in total amounts between about 0.1 wt.% and about 10 wt.%.

[0013] vii) one or more thermoplastic polymers, the total amount of which is between about 1 wt.% and about 20 wt.%; and

[0014] viii) Non-spherical magnetic or magnetizable pigment particles, in total amount between about 1 wt.% and about 40 wt.%.

[0015] The weight percentages are based on the total weight of the UV-Vis radiation-curable coating composition.

[0016] Preferably, the UV-Vis radiation-curable coating composition described herein comprises:

[0017] i) One or more (meth)acrylate oligomers described herein are present in a total amount between about 2 wt.% and 5 wt.%;

[0018] ii) One or more (meth)acrylate monomers described herein, present in a total amount between about 2 wt.% and 15 wt.%;

[0019] iii) One or more cyclic ether compounds described herein, present in a total amount between about 10 wt.% and 35 wt.%;

[0020] iv) One or more vinyl ether compounds described herein, present in a total amount between about 15 wt.% and 40 wt.%;

[0021] v) One or more onium photoinitiators described herein are present in a total amount between about 1 wt.% and 5 wt.%;

[0022] vi) One or more photoinitiators described herein are selected from the group consisting of: alkoxyketones, acetophenones, benzophenones, ketone sulfones, benzyl ketal, benzoyl ethers, phosphine oxides, phenyl glyoxylates, coumarins, camphorquinones, and mixtures thereof, in total amounts between about 1 wt.% and 5 wt.%.

[0023] vii) One or more thermoplastic polymers described herein, in total amounts between about 3 wt.% and 15 wt.%; and

[0024] viii) The non-spherical magnetic or magnetizable pigment particles are present in a total amount between about 3 wt.% and 35 wt.%;

[0025] The weight percentages are based on the total weight of the UV-Vis radiation-curable coating composition.

[0026] The UV-Vis radiation-curable coating composition described herein may further include:

[0027] ix) Optionally one or more photosensitizers, wherein, when present, the one or more photosensitizers are preferably present in a total amount of about 0.1 wt.% to about 5 wt.%; and / or

[0028] x) Optionally, one or more fillers or extenders are selected, wherein, when present, the one or more fillers or extenders are preferably present in a total amount of about 0.1 wt.% to about 10 wt.%; and / or

[0029] xi) Optionally one or more UV stabilizers, wherein, when present, the one or more UV stabilizers are preferably present in a total amount of about 0.1 wt.% to about 10 wt.%; and / or

[0030] xii) One or more color-constant coloring components are optionally present, wherein, when present, the one or more color-constant coloring components are preferably present in a total amount of about 0.05 wt.% to about 5 wt.%.

[0031] xiii) One or more solvents may be selected, wherein, when present, the one or more solvents are present in a total amount of less than about 15 wt.%; and / or

[0032] xiv) Select one or more markers or tracers and / or one or more machine-readable materials; and / or

[0033] xv) Select one or more additives from the group consisting of: thickeners, surfactants, antisettling agents, plasticizers, defoamers, waxes and mixtures thereof;

[0034] The weight percentages are based on the total weight of the UV-Vis radiation-curable coating composition.

[0035] This document also describes a method for producing an optical effect layer (OEL), the method comprising the steps of: a) applying a UV-Vis radiation-curable coating composition to a substrate; b) exposing the coating in a first state to a magnetic field generated by a magnetic field generating device, thereby orienting at least a portion of the non-spherical magnetic or magnetizable pigment particles described herein; and c) curing the coating to a second state to fix the non-spherical magnetic or magnetizable pigment particles at their adopted positions and orientations.

[0036] This document also describes optical effect layers (OELs) and security documents produced by the methods described herein, as well as decorative elements and objects containing one or more optical OELs as described herein.

[0037] This document also describes a method of manufacturing a security document or decorative element or object, comprising a) providing a security document or decorative element or object, and b) providing optical effect layers as described herein, particularly those obtained by the methods described herein, such that they are contained within the security document or decorative element or object.

[0038] The UV-Vis radiation-curable coating compositions described herein are particularly suitable for producing mechanically and chemically resistant optical effect layers (OELs) on high-demand documents, such as valuable documents including banknotes. These documents are exposed to mechanical and chemical constraints such as folds, wrinkles, and substrate creases, resulting in reduced lifespan and thus requiring increased replacement rates at additional cost. Furthermore, the UV-Vis radiation-curable coating compositions described herein allow for the fabrication of these highly durable OELs on valuable documents, wherein the OELs can be produced efficiently in terms of speed and drying performance. Attached Figure Description

[0039] Figure 1 Figure 4 schematically illustrates the invention and is not drawn to scale. The optical effect layer (OEL) produced by the UV-Vis radiation-curable coating composition is described in more detail with reference to the accompanying drawings and specific embodiments, wherein...

[0040] Figure 1 Photographic images of OELs produced using comparative compositions (C1-C3) and UV-Vis radiation-curable coating compositions according to the present invention (E1-E2) are shown.

[0041] Figure 2 Photographic images of OELs produced with the comparative compositions (C2-C3) and the UV-Vis radiation-curable coating compositions (E1-E2) according to the present invention, following the drying wrinkling test (mechanical resistance test) described herein.

[0042] Figure 3 Photographic images of OELs produced with the comparative composition (C2) and the UV-Vis radiation-curable coating compositions (E1-E2) according to the present invention, following the washing machine test (mechanical resistance test) described herein.

[0043] Figure 4 schematically illustrates the process for generating Figure 1 The magnetic component of the OEL shown. Detailed Implementation

[0044] definition

[0045] The following definitions are used to clarify the meaning of terms discussed in the specification and defined in the claims.

[0046] As used in this article, the term "at least one" is intended to define one or more than one, such as one, two, or three.

[0047] As used herein, the term "about" means that the quantity or value in discussion can be a specific value or some other value near it. Generally, the term "about" to indicate a value is intended to represent a range within ±5% of that value. As an example, the phrase "about 100" means a range of 100 ± 5, that is, a range of 95 to 105. Generally, when the term "about" is used, similar results or effects according to the invention can be expected to be obtained within ±5% of the indicated value.

[0048] As used herein, the term “and / or” means that all or only one of the elements of the group may be present. For example, “A and / or B” should mean “A only, or B only, or both A and B”. In the case of “A only”, the term also covers the possibility that B is not present, i.e., “A only, without B”.

[0049] As used herein, the term "comprising" is intended to be non-exclusive and open-ended. Thus, a coating composition comprising, for example, compound A may comprise other compounds besides A. However, as in particular embodiments thereof, the term "comprising" also encompasses the more restrictive meanings of "consistently composed of" and "composed of," such that, for example, "a dampening solution comprising A, B, and optionally C" may also consist (substantially) of A and B, or (substantially) of A, B, and C.

[0050] As used herein, the term "Optical Effect Layer (OEL)" refers to a coating containing oriented magnetic or magnetizable pigment particles, wherein the magnetic or magnetizable pigment particles are oriented by a magnetic field, and wherein the oriented magnetic or magnetizable pigment particles are fixed / frozen in their orientation and position (i.e., after curing) to form a magnetically induced image.

[0051] The term "coating composition" refers to any composition capable of forming an optical effect layer (OEL) on a solid substrate, and which can preferably, but not exclusively, be applied by a printing method.

[0052] As used herein, the term "wet" refers to a coating that has not yet cured, such as a coating in which non-spherical magnetic or magnetizable pigment particles can still change their position and orientation under the influence of external forces acting on them.

[0053] The term "secure document" refers to a document that is typically protected against forgery or tampering by at least one security feature. Examples of secure documents include, but are not limited to, documents of value and goods of value.

[0054] The term "security feature" is used to refer to images, patterns, or graphic elements that can be used for authentication purposes.

[0055] Where this specification refers to "preferred" embodiments / features, combinations of such "preferred" embodiments / features should also be considered disclosed, provided that such combinations of "preferred" embodiments / features are technically meaningful.

[0056] The UV-Vis radiation-curable coating composition described herein may comprise i) one or more (meth)acrylate oligomers, wherein, when present, the one or more (meth)acrylate oligomers are present in a total amount between about 1 wt.% and 10 wt.%, preferably between about 2 wt.% and 5 wt.%, the weight percentages being based on the total weight of the radiation-curable coating composition. According to one embodiment, the UV-Vis radiation-curable coating composition described herein comprises i) the amount of (meth)acrylate oligomers described herein. As used herein, (meth)acrylate oligomers refer to relatively high molecular weight compounds with a weight-average molecular weight (MW) ≥300 g / mol, preferably ≥500 g / mol. The (meth)acrylate oligomers may be branched or substantially linear, and one or more (meth)acrylate functional groups may be terminal groups and / or pendant side groups bonded to the oligomer backbone, respectively. Preferably, the (meth)acrylate oligomer is selected from the group consisting of: (meth)acrylate oligomers, urethane (meth)acrylate oligomers, polyester (meth)acrylate oligomers, polyether (meth)acrylate oligomers, epoxy (meth)acrylate oligomers, and mixtures thereof, more preferably from the group consisting of: epoxy (meth)acrylate oligomers and mixtures thereof.

[0057] In the context of this invention, the term "(meth)acrylate" refers to acrylates and the corresponding methacrylates.

[0058] The UV-Vis radiation-curable coating compositions described herein comprise ii) one or more (meth)acrylate monomers, in a total amount of about 1 wt.% to about 20 wt.%, preferably about 2 wt.% to about 15 wt.%, wherein said one or more monomers are different from the (meth)acrylate oligomers of i), and the weight percentages are based on the total weight of the UV-Vis radiation-curable coating composition. Preferably, the one or more (meth)acrylates described herein are selected from the group consisting of: epoxy (meth)acrylates, (meth)acrylated oils, polyesters and polyethers (meth)acrylates, aliphatic or aromatic urethane (meth)acrylates, silicone (meth)acrylates, acrylic (meth)acrylates, and mixtures thereof. Suitable examples of (meth)acrylates include tri(meth)acrylates, tetra(meth)acrylates, and mixtures thereof.

[0059] Suitable examples of tri(meth)acrylates include, but are not limited to, trimethylolpropane triacrylate; trimethylolpropane triacrylate; alkoxylated (especially ethoxylated or propoxylated) trimethylolpropane triacrylate; alkoxylated (especially ethoxylated or propoxylated) trimethylolpropane triacrylate; alkoxylated (especially ethoxylated or propoxylated) glycerol triacrylate; pentaerythritol triacrylate; alkoxylated (especially ethoxylated or propoxylated) pentaerythritol triacrylate and mixtures thereof, preferably selected from the group consisting of: trimethylolpropane triacrylate; alkoxylated (especially ethoxylated or propoxylated) trimethylolpropane triacrylate; alkoxylated (especially ethoxylated or propoxylated) glycerol triacrylate; pentaerythritol triacrylate and mixtures thereof.

[0060] Suitable examples of tetra(meth)acrylates include, but are not limited to, di(trimethylolpropane)tetra(meth)acrylate; pentaerythritol tetra(meth)acrylate; alkoxylated (e.g., ethoxylated and propoxylated) pentaerythritol tetra(meth)acrylates and mixtures thereof, preferably selected from the group consisting of: di(trimethylolpropane)tetra(meth)acrylate; alkoxylated pentaerythritol tetra(meth)acrylates and mixtures thereof.

[0061] The UV-Vis radiation-curable coating compositions described herein may further comprise one or more UV-Vis curable diluents selected from the group consisting of: mono(meth)acrylates; di(meth)acrylates and mixtures thereof. Suitable examples of mono(meth)acrylates include, but are not limited to, alkyl (meth)acrylates; cycloalkyl (meth)acrylates; benzyl (meth)acrylates; phenyl (meth)acrylates (including phenoxyalkyl (meth)acrylates such as phenoxyethyl acrylate); cyclic trimethylolpropane acetal acrylates; tetrahydrofurfuryl acrylate; aliphatic urethane (meth)acrylates and their alkoxylated (especially ethoxylated or propoxylated) compounds. Suitable examples of di(meth)acrylates include, but are not limited to, ethylene glycol diacrylate; ethylene glycol dimethacrylate; 1,4-butanediol diacrylate; 1,4-butanediol dimethacrylate; 1,3-butanediol diacrylate; 1,3-butanediol dimethacrylate; 2-methyl-1,3-propanediol diacrylate; 3-methyl-1,5-pentanediol diacrylate; 2-butyl-2-ethyl-1,3-propanediol diacrylate; 1,6-hexanediol diacrylate; 1,6-hexanediol dimethacrylate; neopentanediol diacrylate; neopentanediol dimethacrylate; 1,9-nonanediol diacrylate; 1,9-nonanediol dimethacrylate; 1,10-decanediol diacrylate; 1,10-decanediol dimethacrylate; alkoxylation (especially ethoxylation) Propoxylated 1,6-hexanediol diacrylate; propoxylated neopentyl glycol diacrylate; ethoxylated 2-methyl-1,3-propanediol diacrylate; tricyclodecanediethanol diacrylate; diethylene glycol diacrylate; diethylene glycol dimethacrylate; dipropylene glycol diacrylate; triethylene glycol diacrylate; triethylene glycol dimethacrylate; tripropylene glycol diacrylate; tripropylene glycol dimethacrylate; tetraethylene glycol diacrylate; tetraethylene glycol dimethacrylate; polyethylene glycol 200 / 400 / 600 diacrylate; polyethylene glycol 200 / 400 / 600 dimethacrylate; ethoxylated (EO2 / EO3 / EO4 / EO10) bisphenol A diacrylate; and ethoxylated (EO2 / EO3 / EO4 / EO10) bisphenol A dimethacrylate.

[0062] The UV-Vis radiation-curable coating composition described herein comprises iii) one or more cyclic ether compounds, preferably selected from the group consisting of epoxides, oxetanes and mixtures thereof, more preferably alicyclic epoxides, oxetanes and mixtures thereof, in total amounts between about 5 wt.% and about 40 wt.%, preferably between about 10 wt.% and about 35 wt.%, the weight percentages being based on the total weight of the UV-Vis radiation-curable coating composition.

[0063] According to one embodiment, the UV-Vis radiation-curable coating composition described herein comprises at least one cyclic ether compound, preferably at least one alicyclic epoxide, wherein the alicyclic epoxide may be bifunctional or multifunctional. The UV-Vis radiation-curable coating composition comprising at least one alicyclic epoxide described herein may further comprise at least one oxetane described herein, wherein the at least one alicyclic epoxide and the at least one oxetane are present in a total amount of about 5 wt.% to about 40 wt.%, preferably about 10 wt.% to about 35 wt.%, based on the total weight of the UV-Vis radiation-curable coating composition. As is well known to those skilled in the art, alicyclic epoxides are cationic curable monomers that contain at least a substituted or unsubstituted epoxycyclohexyl residue:

[0064] .

[0065] Preferably, the alicyclic epoxides described herein comprise at least one cyclohexane ring and / or at least two epoxy groups, preferably at least one cyclohexane ring and at least two epoxy groups. Preferred alicyclic epoxides comprise more than one (i.e., at least two) cyclohexyl groups and preferably have the structural formula (I):

[0066]

[0067] (I)

[0068] Wherein -X- represents a single bond or a divalent group containing one or more atoms. The alicyclic epoxide of general formula (I) is optionally substituted with one or more straight-chain or branched alkyl groups containing 1 to 10 carbon atoms (such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, hexyl, octyl and decyl), preferably straight-chain or branched alkyl groups containing 1 to 3 carbon atoms (such as methyl, ethyl, n-propyl and isopropyl).

[0069] According to one embodiment, -X- is a divalent hydrocarbon group, which can be a straight-chain or branched alkylene group containing 1 to 18 carbon atoms, wherein examples of the straight-chain or branched alkylene group include, but are not limited to, methylene, methylmethylene, dimethylmethylene, ethylene, propylene, and trimethylene.

[0070] According to one embodiment, -X- is a divalent alicyclic hydrocarbon group or a cyclohexylene group, such as 1,2-cyclopentylene, 1,3-cyclopentylene, cyclopentylene, 1,2-cyclohexylene, 1,3-cyclohexylene, 1,4-cyclohexylene, and cyclohexylene.

[0071] According to one embodiment, -X- is a divalent group comprising one or more oxygen-containing linking groups, wherein the oxygen-containing linking groups are selected from the group consisting of -C(=O)-, -OC(=O)O-, -C(=O)O-, and -O-. Preferably, the alicyclic epoxide is an alicyclic epoxide of general formula (II), wherein -X- is a divalent group comprising one or more oxygen-containing linking groups, wherein the oxygen-containing linking groups are selected from the group consisting of -C(=O)-, -OC(=O)O-, -C(=O)O-, and -O-, and more preferably alicyclic epoxides of general formula (Ia), (Ib), or (Ic) as defined below:

[0072]

[0073] (Ia)

[0074] in,

[0075] X1 may be the same or different each time it appears, and is a straight-chain or branched alkyl group (such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, hexyl, octyl and decyl) containing 1 to 10 carbon atoms, and preferably a straight-chain or branched alkyl group (such as methyl, ethyl, n-propyl and isopropyl) containing 1 to 3 carbon atoms.

[0076] X2 may be the same or different each time it appears, and is a straight-chain or branched alkyl group containing 1 to 10 carbon atoms (such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, hexyl, octyl, and decyl), and preferably a straight-chain or branched alkyl group containing 1 to 3 carbon atoms (such as methyl, ethyl, n-propyl, and isopropyl); and

[0077] l1 and l2 are independent integers that are contained between 0 and 9, preferably between 0 and 3, and more preferably 0;

[0078]

[0079] (Ib)

[0080] in,

[0081] X1 may be the same or different each time it appears, and is a straight-chain or branched alkyl group (such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, hexyl, octyl and decyl) containing 1 to 10 carbon atoms, and preferably a straight-chain or branched alkyl group (such as methyl, ethyl, n-propyl and isopropyl) containing 1 to 3 carbon atoms.

[0082] X2 may be the same or different each time it appears, and is a straight-chain or branched alkyl group containing 1 to 10 carbon atoms (such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, hexyl, octyl, and decyl), and preferably a straight-chain or branched alkyl group containing 1 to 3 carbon atoms (such as methyl, ethyl, n-propyl, and isopropyl); and

[0083] l1 and l2 are independent integers that are contained between 0 and 9, preferably between 0 and 3, and more preferably 0;

[0084] -X3- is a single bond or a straight-chain or branched divalent hydrocarbon group containing 1 to 10 carbon atoms, preferably 3 to 8 carbon atoms, such as alkylene groups including trimethylene, tetramethylene, hexamethylene and 2-ethylhexene, and cycloalkylene groups such as 1,2-cyclohexene, 1,3-cyclohexene and 1,4-cyclohexene and cyclohexene;

[0085]

[0086] (Ic)

[0087] in,

[0088] X1 can be the same or different each time it appears, and is a straight-chain or branched alkyl group containing 1 to 3 carbon atoms, such as methyl, ethyl, n-propyl and isopropyl.

[0089] X2 can be the same or different each time it appears, and it is a straight-chain or branched alkyl group containing 1 to 3 carbon atoms, such as methyl, ethyl, n-propyl, and isopropyl; and

[0090] l1 and l2 are independent integers that are contained between 0 and 9, preferably between 0 and 3, and more preferably 0.

[0091] Preferred alicyclic epoxides of general formula (Ia) include, but are not limited to, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate; 3,4-epoxy-6-methyl-cyclohexylmethyl-3,4-epoxy-6-methylcyclohexane carboxylate; 3,4-epoxy-2-methyl-cyclohexylmethyl-3,4-epoxy-2-methylcyclohexane carboxylate; and 3,4-epoxy-4-methyl-cyclohexylmethyl-3,4-epoxy-4-methylcyclohexane carboxylate.

[0092] Preferred alicyclic epoxides of general formula (Ib) include, but are not limited to, bis(3,4-epoxycyclohexylmethyl) adipate; bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate; bis(3,4-epoxycyclohexylmethyl) oxalate; bis(3,4-epoxycyclohexylmethyl) heptanate; and bis(3,4-epoxycyclohexylmethyl) sebacate.

[0093] Other alicyclic epoxides include alicyclic epoxides of general formula (II-a) and alicyclic epoxides of general formula (II-b), which are optionally substituted with one or more straight-chain or branched alkyl groups containing 1 to 10 carbon atoms (such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, hexyl, octyl, and decyl), preferably straight-chain or branched alkyl groups containing 1 to 3 carbon atoms (such as methyl, ethyl, n-propyl, and isopropyl).

[0094]

[0095] (II-a)

[0096]

[0097] (II-b).

[0098] The alicyclic epoxides described in this article can be hydroxyl-modified or (meth)acrylate-modified.

[0099] Oxycyclic butane compounds are known in the art to accelerate curing and reduce tack, thus limiting the risk of blocking and set-off when printed sheets are stacked immediately after printing and curing. Preferred examples of oxycyclic butanes include trimethylene oxide. (oxide); 3,3-dimethyloxetane; trimethylolpropaneoxetane; 2-ethyl-2-hydroxymethyloxetane; 3-ethyl-3-hydroxymethyloxetane; 3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane; 3,3-dicyclomethyloxetane; 3-ethyl-3-phenoxymethyloxetane; bis([1-ethyl(3-oxetane)]methyl) ether; 1,4-bis[3-ethyl-3-oxetanemethoxy)methyl]benzene; 3,3-dimethyl-2(p-methoxy-phenyl)oxetane; 3-ethyl-[(tri-ethoxysilylpropoxy)methyl]oxetane; 4,4-bis(3-ethyl-3-oxetane)methoxymethyl]biphenyl and 3,3-dimethyl-2(p-methoxy-phenyl)oxetane. The one or more oxetanes described herein may be hydroxyl-modified or (meth)acrylate-modified. In the context of this invention, the term "(meth)acrylate" refers to acrylates and their corresponding methacrylates.

[0100] The UV-Vis radiation-curable coating compositions described herein comprise (iv) one or more vinyl ether compounds, in total amounts between about 10 wt.% and about 50 wt.%, preferably between about 15 wt.% and about 40 wt.%, the weight percentages being based on the total weight of the UV-Vis radiation-curable coating composition. Vinyl ether compounds are known in the art to accelerate curing and reduce tack, thus limiting the risk of sticking and smudging when printed substrates are stacked immediately after printing and curing.

[0101] Examples of preferred vinyl ether compounds include methyl vinyl ether; ethyl vinyl ether; n-propyl vinyl ether; n-butyl vinyl ether; isobutyl vinyl ether; ethylhexyl vinyl ether; octadecyl vinyl ether; dodecyl vinyl ether; isopropyl vinyl ether; tert-butyl vinyl ether; tert-amyl vinyl ether; cyclohexyl vinyl ether; cyclohexanediol monovinyl ether; cyclohexanediol divinyl ether; 4-(ethyleneoxymethyl)cyclohexylmethyl benzoate; phenyl vinyl ether; methyl phenyl vinyl ether; methoxyphenyl vinyl ether; 2-chloroethyl vinyl ether; 2-hydroxyethyl vinyl ether; 4-hydroxybutyl vinyl ether; 1,6-hexanediol monovinyl ether; ethylene glycol divinyl ether; ethylene glycol monovinyl ether; 1,4-butanediol divinyl ether; 1,6-hexanediol divinyl ether; 4-(ethyleneoxy)butylbenzoate; bis[4-(ethyleneoxy)butyl]adip ... [4-(ethoxymethyl)cyclohexylmethyl]glutarate; 4-(ethoxy)butyl stearate; trimethylolpropane trivinyl ether; propylene carbonate ether; diethylene glycol monovinyl ether; diethylene glycol divinyl ether; ethylene glycol butyl vinyl ether; dipropylene glycol divinyl ether; triethylene glycol divinyl ether; triethylene glycol methyl vinyl ether; triethylene glycol monobutyl vinyl ether; tetraethylene glycol divinyl ether; poly( Tetrahydrofuran (DEF); polyethylene glycol-520 methyl vinyl ether; pluriol-E200 DEF; tris[4-(ethoxy)butyl]trimethacrylate; 1,4-bis(2-ethoxyethoxy)benzene; 2,2-bis(4-ethoxyethoxyphenyl)propane; bis[4-(ethoxy)methyl]cyclohexyl]methyl]terephthalate; bis[4-(ethoxy)methyl]cyclohexyl]methyl]isophthalate. According to one embodiment, the UV-Vis radiation-curable coating composition described herein comprises (iv) two or more vinyl ether compounds, in total amounts between about 10 wt.% and about 50 wt.%, preferably between about 15 wt.% and about 40 wt.%, the weight percentages being based on the total weight of the UV-Vis radiation-curable coating composition.

[0102] The UV-Vis radiation-curable coating composition described herein comprises (v) one or more onium photoinitiators, the total amount of which is between about 0.1 wt.% and about 10 wt.%, preferably between about 1 wt.% and about 5 wt.%, the weight percentages being based on the total weight of the UV-Vis radiation-curable coating composition. The one or more onium salts described herein are preferably selected from the group consisting of: nitrogen onium salts, oxyonium salts, iodonium salts, sulfonium salts, and mixtures thereof, more preferably from the group consisting of: oxyonium salts, iodonium salts, sulfonium salts, and mixtures thereof, and even more preferably from the group consisting of: iodonium salts, sulfonium salts, and mixtures thereof.

[0103] The one or more iodonium salts described herein have a cationic moiety and an anionic moiety, wherein the anionic moiety is preferably BF4. - B(C6F5)4 - PF6 - , (PF 6-m (C n F 2n-1 ) m ) - (where m is an integer from 1 to 5, and n is an integer from 1 to 4), AsF6 - SbF6 - CF3SO3 - Perfluoroalkyl sulfonate or pentafluorohydroxyantimonate, more preferably SbF6 - PF6 - Or B(C6F5)4 - Furthermore, the cation moiety is preferably an aromatic iodonium ion, more preferably an iodonium ion containing two aryl groups, wherein the two aryl groups may be independently substituted by one or more alkyl groups (such as methyl, ethyl, isobutyl, tert-butyl, etc.), one or more alkoxy groups, one or more nitro groups, one or more halogen-containing groups, one or more hydroxyl groups, or combinations thereof.

[0104] The one or more sulfonium salts described herein have a cationic moiety and anionic moiety, wherein the anionic moiety is preferably BF4. - B(C6F5)4 - PF6 - , (PF 6-m (C n F 2n-1 ) m ) - (where m is an integer from 1 to 5, and n is an integer from 1 to 4), AsF6 - SbF6 - CF3SO3 - Perfluoroalkyl sulfonate or pentafluorohydroxyantimonate, more preferably SbF6 - or PF6- Furthermore, the cationic portion is preferably an aromatic sulfonium ion, more preferably a sulfonium ion containing two or more aryl groups, wherein the two or more aryl groups may be independently substituted by one or more alkyl groups (such as methyl, ethyl, isobutyl, tert-butyl, etc.), one or more alkoxy groups, one or more aryloxy groups, one or more halogen-containing groups, one or more hydroxyl groups, or combinations thereof.

[0105] The UV-Vis radiation-curable coating composition described herein comprises vi) one or more photoinitiators selected from the group consisting of: hydroxy ketones (e.g., α-hydroxy ketones), alkoxy ketones (e.g., α-alkoxy ketones), acetophenone, benzophenone, ketone sulfones, benzyl ketal, benzoyl ether, phosphine oxides, phenyl glyoxylates, coumarin, camphorquinone, and mixtures thereof, preferably hydroxy ketones (e.g., α-hydroxy ketones), in a total amount between about 0.1 wt.% and about 10 wt.%, more preferably between about 1 wt.% and about 5 wt.%, the weight percentages being based on the total weight of the UV-Vis radiation-curable coating composition. Preferably, the photoinitiator vi) is selected from the group consisting of: phosphine oxides, hydroxy ketones, and mixtures thereof, more preferably hydroxy ketones (e.g., α-hydroxy ketones).

[0106] The UV-Vis radiation-curable coating compositions described herein may further include (ix) one or more photosensitizers. The photosensitizers are activated by more than one wavelength emitted by a UV-Vis light source and reach an excited state. The excited photosensitizers transfer energy to more than one photoinitiator or electrons. Either process, in turn, initiates the polymerization process. The UV-Vis radiation-curable coating compositions described herein may further include one or more photosensitizers in combination with more than one of the photoinitiators (v) and (vi) described herein to achieve efficient curing. Suitable examples of photosensitizers are known to those skilled in the art (e.g., in Industrial Photoinitiators, WA Green, CRC Press, 2010, Table 8.1, page 170). Preferably, one or more photosensitizers are selected from the group consisting of: thioxanthone compounds, anthracene compounds, naphthalene compounds, titanoceramic compounds, and mixtures thereof; more preferably, they are selected from the group consisting of: thioxanthone compounds (including but not limited to isopropyl-thioxanthone (ITX), 1-chloro-2-propoxy-thioxanthone (CPTX), 2-chloro-thioxanthone (CTX) and 2,4-diethyl-thioxanthone (DETX) and mixtures thereof and their oligomer or polymeric forms), anthracene compounds (such as 9,10-diethoxyanthracene and 9,10-dibutoxyanthracene), naphthalene compounds (such as 1,4-diethoxynaphthalene), and mixtures thereof. When present, one or more photosensitizers are preferably present in a total amount of about 0.1 wt.% to about 5 wt.%, more preferably about 0.2 wt.% to about 1 wt.%, the weight percentages being based on the total weight of the UV-Vis radiation-curable coating composition.

[0107] The UV-Vis radiation-curable coating composition described herein comprises vii) one or more thermoplastic polymers, the total amount of which is between about 1 wt.% and about 20 wt.%, preferably between about 3 wt.% and about 15 wt.%, the weight percentages being based on the total weight of the UV-Vis radiation-curable coating composition. Preferably, the one or more thermoplastic polymers are selected from the group consisting of: polyvinyl butyral (PVB), polyamide, polyvinyl chloride (PVC), polyester, polyacetal, polyolefin, styrene polymers, polycarbonate, polyarylate, polyimide, polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyphenylene resins, polysulfone, and mixtures thereof, more preferably selected from the group consisting of: polyvinyl butyral (PVB) and mixtures thereof. According to one embodiment, at least one of the one or more thermoplastic polymers is polyvinyl butyral (PVB) and / or polyvinyl chloride (PVC).

[0108] The UV-Vis radiation-curable coating composition described herein comprises (viii) non-spherical magnetic or magnetizable pigment particles, the total amount of which is between about 1 wt.% and about 40 wt.%, preferably between about 3 wt.% and about 35 wt.%, more preferably between about 5 wt.% and about 30 wt.%, the weight percentages being based on the total weight of the UV-Vis radiation-curable coating composition. The non-spherical magnetic or magnetizable pigment particles described herein are preferably prolate or oblate ellipsoid-shaped, flake-shaped or needle-shaped magnetic or magnetizable pigment particles, or a mixture of two or more thereof, more preferably flake-shaped particles.

[0109] The non-spherical magnetic or magnetizable pigment particles described herein are defined as having an isotropic reflectivity relative to incident electromagnetic radiation due to their non-spherical shape, for which the cured binder material is at least partially transparent. As used herein, the term "anisotropic reflectivity" means that the proportion of radiation incident from a first angle that is reflected by the particle to a certain (viewing) direction (second angle) is a function of the particle orientation; that is, a change in particle orientation relative to the first angle can result in different magnitudes of reflection to the viewing direction. Preferably, the non-spherical magnetic or magnetizable pigment particles described herein have an isotropic reflectivity relative to incident electromagnetic radiation in some portions or over the entire wavelength range of about 200 nm to about 2500 nm, more preferably about 400 nm to about 700 nm, such that a change in particle orientation results in a change in the direction of reflection by the particle. As those skilled in the art will know, the magnetic or magnetizable pigment particles described herein differ from conventional pigments because conventional pigment particles exhibit the same color and reflectivity regardless of particle orientation, while the magnetic or magnetizable pigment particles described herein exhibit reflectivity or color, or both, depending on particle orientation.

[0110] The UV-Vis radiation-curable coating compositions and coatings described herein comprise the non-spherical, preferably flake-shaped magnetic or magnetizable pigment particles described herein, preferably in an amount of about 1 wt.% to about 40 wt.%, more preferably between about 3 wt.% and about 35 wt.%, and more preferably between about 5 wt.% and about 30 wt.%, the weight percentages being based on the total weight of the UV-Vis radiation-curable coating composition or coating.

[0111] Suitable examples of non-spherical, preferably plate-like, magnetic or magnetizable pigment particles described herein include, but are not limited to, pigment particles comprising: magnetic metals selected from the group consisting of cobalt (Co), iron (Fe), and nickel (Ni); magnetic alloys of iron, manganese, cobalt, nickel, or mixtures thereof; magnetic oxides of chromium, manganese, cobalt, iron, nickel, or mixtures thereof; or mixtures thereof. 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 thereof can be pure oxides or mixed oxides. Examples of magnetic oxides include, but are not limited to, iron oxides such as hematite (Fe₂O₃) and magnetite (Fe₃O₄), chromium dioxide (CrO₂), magnetic ferrite (MFe₂O₄), magnetic spinel (MR₂O₄), and magnetic hexagonal ferrite (MFe₂O₄). 12 O 19 ), magnetic positive ferrite (RFeO3), magnetic garnet M3R2(AO4)3, where M represents a divalent metal, R represents a trivalent metal, and A represents a tetravalent metal.

[0112] Examples of non-spherical, preferably sheet-like, magnetic or magnetizable pigment particles described herein include, but are not limited to, pigment particles comprising a magnetic layer M, wherein the magnetic layer M is made of one or more magnetic metals such as cobalt (Co), iron (Fe), or nickel (Ni) and magnetic alloys of iron, cobalt, or nickel, wherein the magnetic or magnetizable pigment particles may be a multilayer structure comprising one or more additional layers. Preferably, the one or more additional layers are layers A independently made of one or more, more preferably, silicon dioxide (SiO2), selected from the group consisting of metal fluorides such as magnesium fluoride (MgF2), silicon oxide (SiO), silicon dioxide (SiO2), titanium oxide (TiO2), and aluminum oxide (Al2O3); or layers B independently made of one or more, more preferably, aluminum (Al), 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 silver (Ag), aluminum (Al), chromium (Cr), and nickel (Ni); or combinations of one or more of the layers A as described above and one or more of the layers B as described above. Typical examples of the above-mentioned multilayered sheet-like magnetic or magnetizable pigment particles include, but are not limited to, A / M multilayer structure, A / M / A multilayer structure, A / M / B multilayer structure, A / B / M / A multilayer structure, A / B / M / B multilayer structure, A / B / M / B / A multilayer structure, B / M multilayer structure, B / M / B multilayer structure, M / A / M multilayer structure, B / A / M / A multilayer structure, B / A / M / B multilayer structure, B / A / M / B / A multilayer structure, B / A / M / A / B multilayer structure, B / A / M / A / B multilayer structure, B / A / B / A / M / A / B / A / B multilayer structure, and A / B / A / B / A / M / A / B / A / B / A multilayer structure, wherein layer A, magnetic layer M, and layer B are selected from those mentioned above.

[0113] The UV-Vis radiation-curable coating compositions described herein may comprise non-spherical, preferably sheet-like, optically variable magnetic or magnetizable pigment particles, and / or non-spherical, preferably sheet-like, magnetic or magnetizable pigment particles without optically variable properties. Preferably, at least a portion of the magnetic or magnetizable pigment particles described herein consists of non-spherical, preferably sheet-like, optically variable magnetic or magnetizable pigment particles. In addition to the explicit security provided by the color-changing properties of the optically variable magnetic or magnetizable pigment particles, which allows for easy detection, identification, and / or differentiation using unassisted human senses of articles or security documents bearing inks, coating compositions, or coatings containing the optically variable magnetic or magnetizable pigment particles described herein from their potential for counterfeiting, the optical properties of the optically variable magnetic or magnetizable pigment particles can also be used as a machine-readable tool for identifying OELs. Therefore, the optical properties of the optically variable magnetic or magnetizable pigment particles can simultaneously serve as implicit or semi-implicit security features in authentication processes that analyze the optical (e.g., spectral) properties of the pigment particles, thereby enhancing anti-counterfeiting capabilities.

[0114] The use of non-spherical, preferably flake-shaped, optically variable magnetic or magnetizable pigment particles in the coating used to produce OEL enhances the importance of OEL as a security feature in secure document applications, since this material is reserved for the secure document printing industry and is not commercially available to the public.

[0115] As described above, at least a portion of the preferred non-spherical, preferably sheet-like, magnetic or magnetizable pigment particles is composed of non-spherical, preferably sheet-like, optically variable magnetic or magnetizable pigment particles. These are more preferably selected from the group consisting of: magnetic thin-film interference pigment particles, magnetic cholesterol-type liquid crystal pigment particles, interference-coated pigment particles containing magnetic materials, and mixtures of two or more thereof.

[0116] Magnetic thin-film interference pigment particles are known to those skilled in the art and are disclosed, for example, in US 4,838,648; WO 2002 / 073250 A2; EP 0 686 675 B1; WO 2003 / 000801 A2; US 6,838,166; WO 2007 / 131833 A1; EP 2 402 401 B1; WO 2019 / 103937 A1; EP 3 587 500 A1; EP 3 587 501 A1; EP 3 587 502 A1; EP 3 587503 A1; WO 2020 / 006286 A1; WO 2020 / 131700 A1; US ​​2021 / 0101402; US US 2021 / 038812; US 2022 / 0282094 and the references therein. Preferably, the magnetic thin film interference pigment particles comprise pigment particles having a five-layer Fabry-Perot multilayer structure and / or pigment particles having a six-layer Fabry-Perot multilayer structure and / or pigment particles having a seven-layer Fabry-Perot multilayer structure and / or pigment particles having a nine-layer Fabry-Perot multilayer structure and / or pigment particles having an eleven-layer Fabry-Perot multilayer structure and / or pigment particles having a multilayer structure combining one or more multilayer Fabry-Perot structures.

[0117] The preferred five-layer Fabry-Perot multilayer structure is composed of an absorber / dielectric / reflector / dielectric / absorber multilayer structure, wherein the reflector and / or absorber are also magnetic layers. Preferably, the reflector and / or absorber are magnetic layers containing nickel, iron and / or cobalt, and / or magnetic alloys containing nickel, iron and / or cobalt, and / or magnetic oxides containing nickel (Ni), iron (Fe) and / or cobalt (Co).

[0118] The further preferred five-layer Fabry-Perot multilayer structure is composed of a dielectric / reflector / magnetic material / reflector / dielectric multilayer structure.

[0119] The preferred six-layer Fabry-Perot multilayer structure is composed of an absorber / dielectric / reflector / magnetic material / dielectric / absorber multilayer structure.

[0120] The preferred seven-layer Fabry-Perot multilayer structure is composed of an absorber / dielectric / reflector / magnetic / reflector / dielectric / absorber multilayer structure as disclosed in US 4,838,648.

[0121] The preferred nine-layer Fabry-Perot multilayer structure is composed of a dielectric / absorber / dielectric / reflector / magnetic material / dielectric / absorber / dielectric multilayer structure.

[0122] The preferred eleven-layer Fabry-Perot multilayer structure is composed of an absorber / dielectric / absorber / dielectric / reflector / magnetic body / reflector / dielectric / absorber / dielectric / absorber multilayer structure.

[0123] Preferably, the reflector layer described herein is independently made of: 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 one or more of the group consisting of aluminum (Al), chromium (Cr), nickel (Ni) and their alloys, and even more preferably aluminum (Al). Preferably, the dielectric layer is independently made of: metal fluorides such as magnesium fluoride (MgF2), aluminum fluoride (AlF3), cerium fluoride (CeF3), lanthanum fluoride (LaF3), sodium aluminum fluoride (e.g., Na3AlF6), neodymium fluoride (NdF3), samarium fluoride (SmF3), barium fluoride (BaF2), calcium fluoride (CaF2), lithium fluoride (LiF), and metal oxides such as silicon oxide (SiO), silicon dioxide (SiO2), titanium oxide (TiO2), and aluminum oxide (Al2O3); more preferably, one or more of magnesium fluoride (MgF2) and silicon dioxide (SiO2); and even more preferably, magnesium fluoride (MgF2). Preferably, the absorber layer is independently made of one or more of the following: aluminum (Al), silver (Ag), copper (Cu), palladium (Pd), platinum (Pt), titanium (Ti), vanadium (V), iron (Fe), tin (Sn), tungsten (W), molybdenum (Mo), rhodium (Rh), niobium (Nb), chromium (Cr), nickel (Ni), their metal oxides, their metal sulfides, their metal carbides, and their metal alloys; more preferably, chromium (Cr), nickel (Ni), their metal oxides, and their metal alloys; and even more preferably, chromium (Cr), nickel (Ni), and their metal alloys. Preferably, the magnetic layer comprises nickel (Ni), iron (Fe), and / or cobalt (Co); and / or a magnetic alloy comprising nickel (Ni), iron (Fe), and / or cobalt (Co); and / or a magnetic oxide comprising nickel (Ni), iron (Fe), and / or cobalt (Co). When magnetic thin-film interference pigment particles containing a seven-layer Fabry-Perot structure are preferred, it is particularly preferred that the magnetic thin-film interference pigment particles contain a seven-layer Fabry-Perot absorber / dielectric / reflector / magnetic body / reflector / dielectric / absorber multilayer structure composed of a Cr / MgF2 / Al / M / Al / MgF2 / Cr multilayer structure, wherein M is Ni, Fe or Co.

[0124] The magnetic thin-film interference pigment particles described herein can be multilayer pigment particles considered safe for human health and the environment, and are based on, for example, five-layer Fabry-Perot multilayer structures, six-layer Fabry-Perot multilayer structures, seven-layer Fabry-Perot multilayer structures, nine-layer Fabry-Perot multilayer structures, eleven-layer Fabry-Perot multilayer structures, and multilayer structures having combinations of one or more multilayer Fabry-Perot structures. These pigment particles include one or more magnetic layers comprising a magnetic alloy having a substantially nickel-free composition comprising about 40 wt.% to about 90 wt.% iron, about 10 wt.% to about 50 wt.% chromium, and about 0 wt.% to about 30 wt.% aluminum. Typical examples of multilayer pigment particles considered safe for human health and the environment can be found in EP 2 402 401 B1, the contents of which are incorporated herein by reference in their entirety.

[0125] Suitable magnetic cholesterol-type liquid crystal pigment particles exhibiting optically variable properties include, but are not limited to, magnetic monolayer cholesterol-type liquid crystal pigment particles and magnetic multilayer cholesterol-type liquid crystal pigment particles. Such pigment particles are disclosed, for example, in WO2006 / 063926 A1, US 6,582,781, and US 6,531,221. WO 2006 / 063926 A1 discloses monolayers and pigment particles obtained therefrom having high brightness and color-changing properties, as well as other specific properties such as magnetizability. The disclosed monolayers and pigment particles obtained therefrom by pulverizing said monolayers include three-dimensionally cross-linked cholesterol-type liquid crystal mixtures and magnetic nanoparticles. US 6,582,781 and US 6,410,130 disclose those containing sequence A. 1 / B / A 2 Flaky cholesterol-type multilayer pigment particles, of which A 1 and A 2 They may be the same or different, and each contains at least one cholesterol-type layer, and B is an intermediate layer whose absorption is entirely or partially mediated by layer A. 1 and A 2 The transmitted light imparts magnetism to the intermediate layer. US 6,531,221 also discloses suitable flake-shaped cholesterol-type multilayer pigment particles.

[0126] Suitable interference-coated pigment particles comprising one or more magnetic materials include, but are not limited to, structures consisting of a substrate selected from the group consisting of a core coated with one or more layers, wherein the core or at least one of the layers is magnetic. For example, suitable interference-coated pigment particles comprise a core made of the magnetic materials described above, the core being coated with one or more layers made of one or more metal oxides, or they have a structure consisting of a core made of synthetic or natural mica, layered silicates (e.g., talc, kaolin, and sericite), glass (e.g., borosilicate), silicon dioxide (SiO2), alumina (Al2O3), titanium dioxide (TiO2), graphite, and mixtures thereof, the core being coated with one or more magnetic materials. Furthermore, one or more additional layers, such as a coloring layer, may be present.

[0127] The non-spherical, preferably flake-shaped, magnetic or magnetizable pigment particles described herein preferably have a size d50 (measured by direct optical particle size analyzer) between about 2 μm and about 50 μm.

[0128] The non-spherical, preferably flake-shaped, magnetic or magnetizable pigment particles described herein may be surface-treated to protect them from any degradation that may occur in the coating composition and coating and / or to promote their incorporation into the coating composition and coating; corrosion inhibitors and / or wetting agents may typically be used.

[0129] The UV-Vis radiation-curable coating composition described herein may further comprise x) one or more fillers or extenders, preferably selected from the group consisting of: carbon fiber, talc, mica (silica), wollastonite, calcined clay, kaolin, kaolin, carbonates (e.g., calcium carbonate, sodium aluminum carbonate), silicates (e.g., magnesium silicate, aluminum silicate), sulfates (e.g., magnesium sulfate, barium sulfate), titanates (e.g., potassium titanate), alumina hydrate, silica, fumed silica, montmorillonite, graphite, anatase, rutile, bentonite, vermiculite, zinc dioxide, zinc sulfide, wood flour, quartz powder, natural fibers, synthetic fibers, and combinations thereof. When present, one or more fillers or extenders are preferably present in a total amount of about 0.1 wt.% to about 10 wt.%, more preferably about 0.2 wt.% to about 5 wt.%, the weight percentages being based on the total weight of the UV-Vis radiation-curable coating composition.

[0130] The UV-Vis radiation-curable coating compositions described herein may further include (i) one or more UV stabilizers, particularly UV in-can stabilizers. When present, one or more UV stabilizers are preferably present in a total amount of about 0.1 wt.% to about 10 wt.%, more preferably about 0.2 wt.% to about 5 wt.%, based on the total weight of the UV-Vis radiation-curable coating composition. Examples of UV in-can stabilizers include, but are not limited to, glycerol alkoxylates (e.g., methoxylates, ethoxylates, propoxylates), polyacrylates, piperidine-1-oxy, and hydroquinones (including hydroquinone, alkyl-substituted hydroquinones, and alkoxyalkyl-substituted hydroquinones). Suitable UV in-can stabilizers are, for example, sold by Rahn under the trade name GENORAD, by Kromachem under the trade name FLORSTAB, by 3Dresyns under the name 3D-ADD STAB2 Bio, or by Sitech under the name SR-12UV.

[0131] The UV-Vis radiation-curable coating composition described herein may further comprise (xii) one or more color-constant coloring components (i.e., components without optically variable properties), selected from the group consisting of organic pigment particles, inorganic pigment particles, and organic dyes. When present, the one or more color-constant coloring components are preferably present in a total amount of about 0.05 wt.% to about 5 wt.%, more preferably about 0.1 wt.% to about 3 wt.%, based on the total weight of the UV-Vis radiation-curable coating composition. Optically variable (also known in the art as goniochromatic or color-changing) pigment particles are known to exhibit colors that depend on the viewing angle or angle of incidence. Optically variable pigment particles impart different color impressions at different viewing angles. "Different color impressions" means that the element exhibits a difference in at least one parameter of the CIELAB (1976) system, preferably exhibiting different "a" values ​​at different viewing angles. "Value, different "L" "Value or different "b "Value or expression from "a" “b” " and "L The value is selected from two or three different values. In contrast to optically variable pigment particles that exhibit different colors or color impressions with changing viewing angles, color-constant coloring components do not exhibit color changes or color impression changes with changing viewing angles. For example, a layer or coating containing optically variable pigment particles exhibits a color change from a first color impression CI1 (e.g., green) to a second color impression CI2 (blue) with changing viewing angles (e.g., from a viewing angle of about 90° relative to the plane of the layer or coating to about 22.5° relative to the plane of the layer or coating). According to one embodiment, the UV-Vis radiation-curable coating composition described herein comprises non-spherical, preferably flake-like, optically variable magnetic or magnetizable pigment particles and one or more color-constant coloring components. Preferably, the color of the one or more color-constant coloring components is selected to be the same as or similar to the color of the optically variable magnetic or magnetizable pigment particles at a first viewing angle (e.g., the first color impression CI1 is green), or the same as or similar to the color of the optically variable magnetic or magnetizable pigment particles at a second viewing angle (e.g., the second color impression CI2 is blue), or a color in between.

[0132] The UV-Vis radiation-curable coating composition described herein may further include xiii) one or more solvents to fine-tune the viscosity of the ink. Preferred solvents are polar aprotic solvents exhibiting high boiling points, such as carbonates. Preferred carbonates are alkylene carbonates (e.g., ethylene carbonate, propylene carbonate, and butyl carbonate). Propylene carbonate is particularly preferred due to its high boiling point and favorable ecotoxicity characteristics. When present, one or more solvents are present in a total amount of less than about 15 wt.%, more preferably less than about 5 wt.%, based on the total weight of the UV-Vis radiation-curable coating composition.

[0133] The UV-Vis radiation-curable coating compositions described herein may further comprise one or more markers or tracers and / or one or more machine-readable materials selected from the group consisting of magnetic materials (different from the non-spherical magnetic or magnetizable pigment particles described herein), luminescent materials, electroluminescent materials, upconversion materials, conductive materials, Raman-active materials (including surface-enhanced Raman spectroscopy (SERS) materials), and infrared-absorbing materials. Alternatively, one or more markers or tracers and / or one or more machine-readable materials may be materials that can be authenticated using a microscope. As used herein, the term "machine-readable material" refers to a material exhibiting at least one unique property that can be detected by a device or machine, and the machine-readable material may be included in a coating to enable authentication of the coating or an article containing the coating by using specific equipment for its detection and / or authentication.

[0134] According to one embodiment, the UV-Vis radiation-curable coating composition described herein comprises less than 5 wt.% or about 5 wt.%, preferably between 0 wt.% or about 0 wt.% and less than 5 wt.% or about 5 wt.%, of a polyol having more than three hydroxyl groups per molecule and a hydroxyl value of 550-750 mg KOH / g.

[0135] The UV-Vis radiation-curable coating compositions described herein may further comprise one or more additives, including but not limited to compounds and materials used to adjust the physical, rheological, and chemical parameters of the coating composition, such as viscosity (e.g., thickeners and surfactants), consistency (e.g., antisettling agents and plasticizers), foaming properties (e.g., defoamers), lubricity (waxes), adhesion, antistatic properties, etc. According to one embodiment, the UV-Vis radiation-curable coating compositions described herein further comprise one or more additives selected from the group consisting of: thickeners, surfactants, antisettling agents, plasticizers, defoamers, waxes, and mixtures thereof.

[0136] The additives described herein may be present in coating compositions in amounts and forms known in the art, including so-called nanomaterials, wherein at least one size of the additive is in the range of 1 to 1000 nm.

[0137] According to one embodiment, the UV-Vis radiation-curable coating composition described herein comprises:

[0138] i) Optionally, one or more (meth)acrylate oligomers as described herein, preferably in total amounts as described herein;

[0139] ii) One or more (meth)acrylate monomers described herein are preferably selected from the group consisting of tri(meth)acrylate, tetra(meth)acrylate and mixtures thereof, in total as described herein, wherein the one or more monomers are different from the (meth)acrylate oligomers of i).

[0140] iii) One or more cyclic ether compounds described herein are preferably selected from the group consisting of epoxides, oxetanes and mixtures thereof, more preferably alicyclic epoxides, oxetanes and mixtures thereof, in total amounts as described herein;

[0141] iv) One or more vinyl ether compounds described herein, in total as described herein;

[0142] v) One or more onium photoinitiators described herein, in total as described herein;

[0143] vi) One or more photoinitiators described herein are selected from the group consisting of: alkoxyketones, acetophenones, benzophenones, ketone sulfones, benzyl ketals, benzoyl ethers, phosphine oxides, phenyl glyoxylates, coumarins, camphorquinones, and mixtures thereof, in total amounts as described herein;

[0144] vii) One or more thermoplastic polymers described herein, preferably polyvinyl butyral (PVB), in total as described herein;

[0145] viii) The non-spherical magnetic or magnetizable pigment particles described herein are preferably non-spherical optically variable magnetic or magnetizable pigment particles, the total amount of which is as described herein;

[0146] ix) One or more photosensitizers may be selected, and when present, the one or more photosensitizers are preferably present in the total amount described herein;

[0147] x) One or more fillers or extenders may be selected, in total as described herein;

[0148] xi) One or more UV stabilizers may be selected, in total as described herein;

[0149] xii) One or more color-constant coloring components, the total amount of which is as described herein;

[0150] xiii) One or more solvents may be selected, in total as described herein;

[0151] xiv) Optionally, one or more of the markers or tracers described herein and / or one or more machine-readable materials; and

[0152] xv) Select one or more additives from the group consisting of: thickeners, surfactants, antisettling agents, plasticizers, defoamers, waxes and mixtures thereof.

[0153] The UV-Vis radiation-curable coating compositions described herein can be prepared by dispersing or mixing all the components described herein to form a liquid composition. Alternatively, one or more photoinitiators (v) and (vi) and optionally one or more photosensitizers (ix) can be added to the composition during the dispersion or mixing steps of all other components, or can be added at a later stage, i.e., after the formation of the liquid coating composition.

[0154] This document also describes a method for forming an optical effect layer (OEL) on a substrate, wherein the OEL is based on non-spherical magnetic or magnetizable pigment particles with magnetic orientation as described herein. The method comprises the steps of: a) applying the UV-Vis radiation-curable coating composition described herein onto a substrate as described herein to form a coating; b) exposing the coating in a first state to a magnetic field generated by a magnetic field generating device, thereby orienting at least a portion of the non-spherical magnetic or magnetizable pigment particles described herein; and c) curing the coating to a second state to fix the non-spherical magnetic or magnetizable pigment particles in their adopted positions and orientations.

[0155] The method described herein comprises the following steps: a) applying the UV-Vis radiation-curable coating composition described herein onto a substrate to form a coating, said coating composition being in a first physical state that allows it to be applied as a layer and being in a pre-cured (i.e., wet) state, wherein non-spherical magnetic or magnetizable pigment particles can move and rotate within the binder material. Preferably, step a) is carried out by a printing method, said printing method preferably selected from the group consisting of: screen printing, rotary gravure printing, flexographic printing, gravure printing (also known in the art as engraved copperplate printing, engraved steel mold printing), pad printing and curtain coating, more preferably selected from the group consisting of: gravure printing, screen printing, rotary gravure printing, pad printing and flexographic printing, and even more preferably screen printing, rotary gravure printing, pad printing and flexographic printing.

[0156] The UV-Vis radiation-curable coating compositions described herein can be applied to the substrate described herein in the form of more than one mark. As used herein, the term "mark" shall mean a discontinuous layer, including but not limited to codes, symbols, alphanumeric symbols, graphics, geometric patterns (e.g., circles, triangles, and regular or irregular polygons), letters, words, numbers, signs, pictures, portraits, and combinations thereof. Examples of codes include coded marks such as coded alphanumeric data, one-dimensional barcodes, two-dimensional barcodes, QR codes, and data matrices. The more than one mark described herein can be a solid mark and / or a grid mark.

[0157] Following step a) described herein, the method includes step b) exposing the coating to the magnetic field of a magnetic field generating device to orient at least a portion of the non-spherical magnetic or magnetizable pigment particles.

[0158] According to one embodiment, step b) is performed to uniaxially orient at least a portion of the magnetic or magnetizable pigment particles described herein.

[0159] According to another embodiment in which the pigment particles are flake-shaped magnetic or magnetizable pigment particles, step b) is performed to biaxially oriented at least a portion of the flake-shaped magnetic or magnetizable pigment particles, preferably to biaxially oriented at least a portion of the flake-shaped magnetic or magnetizable pigment particles such that both their X-axis and Y-axis are substantially parallel to the substrate surface.

[0160] According to another embodiment in which the pigment particles are flake-shaped magnetic or magnetizable pigment particles, step b) consists of two steps: a first step includes exposing the coating to the magnetic field of a magnetic field generating device to cause at least a portion of the flake-shaped magnetic or magnetizable pigment particles to be biaxially oriented, and a second step includes exposing the coating to the magnetic field of a second magnetic field generating device to cause at least a portion of the flake-shaped magnetic or magnetizable pigment particles to be uniaxially oriented, wherein the second step is performed partially simultaneously, concurrently, or subsequently with respect to the first step.

[0161] In embodiments where the method described herein includes the step of exposing a coating to the magnetic field of a magnetic field generating device described herein to cause at least a portion of the magnetic or magnetizable pigment particles to be biaxially oriented, the coating may subsequently be exposed to the magnetic field generating device more than once.

[0162] In contrast to uniaxial orientation, where magnetic or magnetizable pigment particles are oriented such that only their principal axes are constrained by a magnetic field, biaxial orientation means oriented such that the sheet-like magnetic or magnetizable pigment particles are constrained by both of their principal axes. That is, each sheet-like magnetic or magnetizable pigment particle can be considered to have a major axis in the plane of the pigment particle and an orthogonal minor axis in the plane of the pigment particle. The major and minor axes of the sheet-like magnetic or magnetizable pigment particles are each oriented according to the magnetic field. In practice, this results in adjacent sheet-like magnetic pigment particles that are close to each other in space being substantially parallel to each other. In other words, biaxial orientation aligns the planes of the sheet-like magnetic or magnetizable pigment particles such that the planes of the pigment particles are oriented substantially parallel to the planes of adjacent (in all directions) sheet-like magnetic or magnetizable pigment particles. The biaxial orientation of the sheet-like magnetic or magnetizable pigment particles described herein results in the sheet-like magnetic or magnetizable pigment particles forming a sheet-like structure whose X-axis and Y-axis are preferably substantially parallel to the substrate surface and are planarized in said two dimensions.

[0163] The means for generating a suitable magnetic field to uniaxially orient the non-spherical magnetic or magnetizable pigment particles described herein are not limited, and include, for example, dipole magnets, multipole magnets such as quadrupole, hexapole, and octupole magnets, and combinations thereof. The following means are provided as illustrative examples.

[0164] Optical effects known as flip-flop effects (also known in the art as switching effects) include a first and second printed portion separated by a transition, wherein pigment particles in the first portion are arranged parallel to a first plane, and pigment particles in the second portion are arranged parallel to a second plane. Methods and magnets for generating said effect are disclosed, for example, in US 2005 / 0106367 and EP 1 819 525 B1.

[0165] Optical effects known as the rolling bar effect, as disclosed in US 2005 / 0106367, can also be produced. The "rolling bar" effect is based on simulating the orientation of pigment particles across a curved surface of a coating. An observer sees specular reflections that move away from or towards the observer as the image is tilted. The pigment particles are arranged in a curved manner, following either a convex curvature (also known in the art as a negative curvature orientation) or a concave curvature (also known in the art as a positive curvature orientation). Methods and magnets for producing this effect are disclosed, for example, in EP 2 263 806 A1, EP 1 674 282 B1, EP 2 263 807 A1, WO2004 / 007095 A2, WO 2012 / 104098 A1, and WO 2014 / 198905 A2.

[0166] This can also produce an optical effect known as the Venetian-blind effect. The Venetian-blind effect involves pigment particles oriented in such a way that, along a specific viewing direction, they make the surface of the underlying substrate visible, making marks or other features present on or in the substrate surface apparent to the observer, while simultaneously obstructing visibility along another viewing direction. Methods and magnets for producing this effect are disclosed, for example, in US 8,025,952 and EP 1,819,525 B1.

[0167] It can also produce an optical effect known as the moving ring effect. The moving ring effect consists of an optical illusory image of an object, such as a funnel, cone, bowl, circle, ellipse, or hemisphere, that appears to move in any xy direction depending on the tilt angle of the optical effect layer. Methods and magnets for producing this effect are disclosed, for example, in EP 1 710 756 A1, US8,343,615, EP 2 306 222 A1, EP 2 325 677 A2, WO 2011 / 092502 A2, US 2013 / 0084411, WO 2014 108404 A2, and WO2014 / 108303 A1.

[0168] It can also produce an optical effect that provides an optical impression of a pattern of light and dark areas that shifts when the effect is tilted. Methods and magnets for producing the effect are disclosed, for example, in WO 2013 / 167425 A1.

[0169] Optical effects can also be produced that give the optical impression of a ring having dimensions that change when the effect is tilted. Methods and magnets for producing these optical effects are disclosed, for example, in WO 2017 / 064052 A1, WO 2017 / 080698 A1 and WO 2017 / 148789 A1.

[0170] It can also produce an optical effect that provides the optical impression of one or more annular bodies having a shape that changes when the optical effect layer is tilted. Methods and magnets for producing said effect are disclosed, for example, in WO 2018 / 054819 A1.

[0171] It can also produce an optical effect that provides a crescent-shaped optical impression that moves and rotates when tilted. Methods and magnets for producing said effect are disclosed, for example, in WO 2019 / 215148 A1.

[0172] An optical effect can be produced that provides the optical impression of a ring-shaped body with varying size and shape when tilted. Methods and magnets for producing said effect are disclosed, for example, in co-pending PCT patent application WO 2020 / 052862 A1.

[0173] An optical effect can be produced that provides an ortho-parallactic effect, i.e., in this case, the form of bright reflective vertical stripes that move in the longitudinal direction when the substrate is tilted about a horizontal / latitude axis, or the form of bright reflective vertical stripes that move in the horizontal / latitude direction when the substrate is tilted about a longitudinal axis. Methods and magnets for producing said effect are disclosed, for example, in WO 2020 / 160993 A1.

[0174] An optical effect can be produced that provides the optical impression of a ring surrounded by more than one ring, wherein the shape and / or brightness of said more than one ring changes upon tilting. Methods and magnets for producing said effect are disclosed, for example, in WO 2020 / 193009 A1.

[0175] An optical effect can be produced that provides an optical impression of multiple dark spots and multiple bright spots, which not only move and / or appear and / or disappear diagonally when the substrate is tilted relative to the vertical / longitudinal axis, but also move and / or appear and / or disappear diagonally when the substrate is tilted. Methods and magnets for producing said effect are disclosed, for example, in WO 2021 / 083808 A1 and WO 2021 / 083809 A1.

[0176] Suitable magnetic field generating devices also include those that can include magnetic plates bearing more than one relief, engraving, or cutout. WO 2005 / 002866 A1 and WO 2008 / 046702 A1 are examples of such engraved magnetic plates.

[0177] Suitable magnetic field generating devices also include those comprising a soft magnetic plate carrying one or more marks in the form of indentations and / or protrusions, or those comprising one or more soft magnetic plates with gaps having one or more mark shapes, wherein the orientation step is performed by an assembly forming a substrate carrying a coating over the soft magnetic plate, and wherein the assembly is moved by a non-uniform magnetic field of a static magnetic field generating device to biaxially orient at least a portion of the sheet-like magnetic or magnetizable pigment particles, as described in WO 2018 / 019594 A1 and WO 2018 / 033512 A1.

[0178] Suitable magnetic field generating devices also include those comprising a soft magnetic plate having one or more gaps for receiving one or more dipole magnets and having one or more indentations and / or one or more protrusions forming one or more continuous ring marks and / or one or more discontinuous ring marks, as described in WO 2020 / 025218 A1; or those comprising a soft magnetic component having one or more gaps and one or more dipole magnets disposed within and / or facing the one or more gaps, and / or a pair or more dipole magnets disposed below the soft magnetic plate and spaced apart from the one or more gaps, as described in WO 2020 / 025482 A1.

[0179] There are no limitations on suitable magnetic field generating devices for biaxially oriented sheet-like magnetic or magnetizable pigment particles as described herein.

[0180] A particularly preferred apparatus for biaxially orienting pigment particles is disclosed in EP 2 157 141 A1. During movement of a substrate carrying a coating containing pigment particles, the apparatus disclosed in EP 2 157 141 A1 provides a dynamic magnetic field that changes its direction, forcing the pigment particles to oscillate rapidly until both the principal axes X and Y become substantially parallel to the substrate surface; that is, the pigment particles rotate until they form stable sheet-like structures, wherein their X and Y axes are substantially parallel to the substrate surface and are planarized in said two dimensions.

[0181] Other particularly preferred devices for biaxially orienting pigment particles include linear permanent magnet Halbach arrays, i.e., devices comprising multiple magnets with different magnetization directions and cylindrical devices. A detailed description of Halbach permanent magnets is given by ZQ Zhu and D. Howe (Halbach permanent magnet machines and applications: a review), IEE. Proc. Electric Power Appl., 2001, 148, pp. 299-308. The magnetic field generated by such a Halbach array has the property that it is concentrated on one side and weakens to almost zero on the other side. Linear Halbach arrays are disclosed, for example, in WO 2015 / 086257 A1 and WO2018 / 019594 A1, and Halbach cylindrical devices are disclosed in EP 3 224 055 B1.

[0182] Another particularly preferred device for biaxially orienting pigment particles is a rotating magnet comprising a disk-shaped rotating magnet or magnetic field generating device magnetized substantially along its diameter. Suitable rotating magnets or magnetic field generating devices are described in US 2007 / 0172261 A1, which generate a radially symmetrical time-varying magnetic field, allowing biaxial orientation of magnetic or magnetizable pigment particles in an uncured coating composition. These magnets or magnetic field generating devices are driven by a shaft (or spindle) connected to an external motor. CN 102529326 B discloses examples of devices comprising rotating magnets suitable for biaxially orienting magnetic or magnetizable pigment particles. In a preferred embodiment, a suitable device for biaxially orienting magnetic or magnetizable pigment particles is a shaftless disk-shaped rotating magnet or magnetic field generating device confined in a housing made of a non-magnetic, preferably non-conductive material, and driven by one or more magnetic coils wound around the housing. Examples of such shaftless disc-shaped rotating magnets or magnetic field generating devices are disclosed in WO 2015 / 082344 A1, WO 2016 / 026896 A1 and WO2018 / 141547 A1.

[0183] Other particularly preferred apparatus for biaxially orienting pigment particles is shown in WO 2021 / 239607 A1. Figure 3 A, and includes a) at least a first group (S1) and a second group (S2), each of the first group and the second group (S1, S2) comprising a first rod-shaped dipole magnet and two second rod-shaped dipole magnets, the magnetic axis of the first rod-shaped dipole magnet being oriented substantially parallel to the substrate during magnetic orientation, and the magnetic axis of the second rod-shaped dipole magnet being oriented substantially perpendicular to the substrate; and b) a pair (P1) of third rod-shaped dipole magnets, the magnetic axis of the third rod-shaped dipole magnet being oriented substantially parallel to the substrate, such as those disclosed in WO 2021 / 239607 A1.

[0184] The method described herein includes step c) of hardening the coating to a second state to fix the non-spherical magnetic or magnetizable pigment particles in their adopted positions and orientations. The hardening step is performed using one or more light sources to cure the coating, wherein the one or more light sources are preferably selected from a group consisting of mercury lamps (preferably medium-pressure mercury lamps), UV-LED lamps, and those described herein in sequence, in order to form one or more optical effect layers (OELs) as described herein. A typical sequence includes using one or more UV-LED lamps in a first step to partially cure the UV-Vis radiation-curable coating composition, and using one or more medium-pressure mercury lamps in a second step. Mercury lamps advantageously emit over a wide wavelength range in the UV-A, UV-B, and UV-C ranges. Step d) of hardening the coating as described herein may be performed partially simultaneously with or after step b) as described herein. "Partially simultaneously" means that the two steps are performed partially concurrently, i.e., the time of each step partially overlaps. In the context described herein, when the hardening / curing step c) is performed partially simultaneously with the orientation step b), it must be understood that the orientation of the non-spherical magnetic or magnetizable pigment particles cured in the coating becomes effective before complete or partial curing.

[0185] This invention provides the methods described herein for producing the optical effect layer (OEL) as described herein, and a substrate comprising one or more optical effect layers (OELs) obtained therefrom. The substrate described herein is preferably selected from the group consisting of: paper or other fibrous materials such as cellulose (including woven and non-woven fibrous materials), paper-containing materials, glass, metals, ceramics, plastics and polymers, metallized plastics or polymers, composite materials, and mixtures or combinations thereof. Typical paper, paper-like, or other fibrous materials are made from various fibers, including but not limited to, abaca, cotton, flax, wood pulp, and blends thereof. As is known to those skilled in the art, cotton and cotton / flax blends are preferred for banknotes, while wood pulp is commonly used for security documents other than banknotes. According to another embodiment, the substrate described herein is based on plastics and polymers, metallized plastics or polymers, composite materials, and mixtures or combinations thereof. Suitable examples of plastics and polymers include: polyolefins such as polyethylene (PE) and polypropylene (PP), including biaxially oriented polypropylene (BOPP); polyamides such as polyethylene terephthalate (PET), polybutanediol terephthalate (PBT), polyethylene 2,6-naphthylene glycol (PEN); and polyesters such as polyvinyl chloride (PVC). (See the trademark Tyvek.) ®Spunbond olefin fibers sold below can also be used as substrates. Typical examples of metallized plastics or polymers include the aforementioned plastic or polymer materials on which metals are deposited continuously or discontinuously on their surfaces. 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 aforementioned plastic or polymer materials can be accomplished by electrodeposition, high-vacuum coating, or sputtering. Typical examples of composite materials include, but are not limited to, multilayer structures or laminates of paper and at least one plastic or polymer material such as those mentioned above, and the incorporation of paper-like or fibrous materials such as those mentioned above, of plastic and / or polymer fibers. Of course, the substrate may further contain additives known to those skilled in the art, such as fillers, sizing agents, brighteners, processing aids, reinforcing or humectant agents, etc. When OEL is used for decorative or cosmetic purposes, including, for example, nail polish, the OEL can be produced on other types of substrates including animal or human nails, artificial nails, or other parts.

[0186] This document also describes a method of manufacturing a security document or decorative element or object, comprising a) providing a security document or decorative element or object, and b) providing one or more optical effect layers as described herein, particularly those obtained by the methods described herein, such that they are contained within the security document or decorative element or object.

[0187] If the OEL generated according to the present invention is applied to a secure document or article, and for the purpose of further enhancing the security level of the secure document or article and its resistance to counterfeiting and illegal copying, the substrate may comprise printed, coated, or laser-marked or laser-perforated markings, watermarks, security threads, fibers, planchettes, luminescent compounds, windows, foils, labels, and combinations thereof. Similarly, for the purpose of further enhancing the security level of secure documents and articles and their resistance to counterfeiting and illegal copying, the substrate may comprise one or more marking substances or tracers and / or machine-readable substances (e.g., luminescent substances, UV / visible / IR absorbing substances, magnetic substances, and combinations thereof).

[0188] If desired, a primer layer may be applied to the substrate prior to step a). This can improve the quality of the OEL described herein or promote adhesion. Examples of such primer layers can be found in WO 2010 / 058026 A2.

[0189] Substrates containing one or more OELs as described herein may be embossed, for example, using gravure plates as described in, for example, WO2012 / 025206 A2 and WO 2019 / 233624 A1.

[0190] The OEL described herein can be used in combination with holograms, microlenses, and / or micromirrors as described in WO 2020 / 244805 A1, EP 3 254 863 A1, US 2008 / 0160226, US 2005 / 0180020, and EP 2 284 017 A1.

[0191] For the purpose of improving durability through stain resistance or chemical resistance and cleanliness, thereby increasing the cycle life of security documents, articles, or decorative elements or objects containing an OEL obtained by the methods described herein, or for the purpose of altering their aesthetic appearance (e.g., optical gloss), one or more protective layers may be applied on top of the OEL. When present, the one or more protective layers are typically made of a protective varnish. The protective varnish may be a radiation-curing composition, a heat-drying composition, or any combination thereof. Preferably, the one or more protective layers are radiation-curing compositions, more preferably UV-Vis curing compositions. The protective layers are typically applied after the OEL has been formed.

[0192] The OEL described herein can be applied directly to a substrate, and the OEL will remain permanently on the substrate (e.g., for banknote applications). Alternatively, the optical effect layer can be applied to a temporary substrate for production purposes, from which the OEL can then be removed. This can, for example, facilitate the formation of the optical effect layer (OEL), particularly when the adhesive material is still in its fluid state. Subsequently, after the coating composition used to generate the OEL has cured, the temporary substrate can be removed from the OEL.

[0193] Alternatively, in another embodiment, the adhesive layer may be present on the substrate containing the OEL, either on the side of the substrate opposite to the side providing the OEL, or on the same side as the OEL and on top of the OEL. Thus, the adhesive layer can be applied to the OEL or the substrate after the curing step has been completed. Such articles can be attached to all kinds of documents or other articles or articles without printing or other processes involving machinery and a considerable amount of work. Alternatively, the substrate containing the OEL described herein may be in the form of a transfer foil, which can be applied to the document or article in a separate transfer step. For this purpose, the substrate is provided with a release coating, on which the OEL is produced, as described herein. More than one adhesive layer may be applied to the optical effect layer thus produced.

[0194] This document also describes substrates containing more than one, i.e., two, three, four, etc., optical effect layers (OELs) obtained by the methods described herein.

[0195] This document also describes articles, documents, particularly security documents, decorative elements, and decorative objects that include an optical effect layer (OEL) produced according to the present invention. Such articles, particularly security documents, decorative elements, or objects, may include more than one (e.g., two, three, etc.) OEL produced according to the present invention.

[0196] As described above, the OEL generated according to the present invention can be used for decorative purposes as well as for protecting and authenticating secure documents.

[0197] Typical examples of decorative elements or objects include, but are not limited to, luxury goods, cosmetic packaging, vehicle parts, electronic / electrical appliances, furniture, and nail products.

[0198] Secure documents include, but are not limited to, documents of value and goods of value. Typical examples of documents of value include, but are not limited to, banknotes, contracts, bills, checks, vouchers, stamp duty stamps and tax labels, and agreements; identity documents such as passports, ID cards, visas, driver's licenses, bank cards, credit cards, transaction cards, passes or cards, admission tickets, public transport tickets, and academic certificates or titles, preferably banknotes, identity documents, grants of rights, driver's licenses, and credit cards. The term "goods of value" refers to packaging materials, particularly those used in cosmetics, nutritional products, pharmaceuticals, alcoholic beverages, tobacco products, beverages or food, electrical / electronic products, textiles, or jewelry—that is, articles that should be protected against counterfeiting and / or illegal reproduction to ensure the contents of the package, such as genuine medicines. Examples of such packaging materials include, but are not limited to, labels such as certified brand labels, tamper-evident labels, and seals. It should be noted that the disclosed substrates, documents of value, and goods of value are given for illustrative purposes only and do not limit the scope of the invention.

[0199] Alternatively, the optical effect layer (OEL) described herein can be produced on an auxiliary substrate, such as, for example, a security thread, security strip, foil, decal, window, or label, and thus transferred to the security document in a separate step.

[0200] Without departing from the spirit of the invention, those skilled in the art can conceive of several modifications to the specific embodiments described above. These modifications are included in the present invention.

[0201] Furthermore, all documents mentioned in the full text of this specification are incorporated herein by reference in their entirety, as fully described herein.

[0202] Example

[0203] The invention will now be described in more detail with reference to non-limiting examples. Examples (E1-E2) and comparative examples (C1-C3) were prepared using the UV-Vis radiation-curable coating compositions described in Table 1, and further details of the compositions according to the invention are provided.

[0204] The UV-Vis radiation-curable coating compositions shown in Table 1 were used to prepare two different sets of samples: the first set was prepared to evaluate the magnetic orientation process applied with different compositions and the visual quality of the OEL thus obtained. Figure 1 ); and a second set of samples was prepared to evaluate the mechanical properties and toughness of the printed and hardened layers. Figure 2 and Figure 3 ).

[0205] Table 1

[0206]

[0207] ( Green to blue color-changing magnetic pigment particles (flake-shaped magnetic pigment particles) with a diameter d50 of about 11 μm and a thickness of about 1 μm were obtained from Viavi Solutions, Santa Rosa, CA.

[0208] 1) The C1 composition is based on WO 2021 / 175 907, Table 3A-2, and is adjusted to contain equivalent wt.% magnetic pigment particles.

[0209] 2) The C2 composition is based on WO 2024 / 028 408, Table 1A, Compos SP1a

[0210] 3) The C3 composition is based on WO 2021 / 239607, Table 1

[0211] First group of samples: Magnetic orientation quality test ( Figure 1 )

[0212] To ensure the same process conditions for Examples E1-E2 and Comparative Examples C1-C3, the five UV-Vis radiation-curable coating compositions in Table 1 were applied collinearly side-by-side to white trust paper (size: 17.5cm × 14.5cm, from Louisenthal) by hand coating using a pipette to form lines (total length approximately 125mm), and simultaneously oriented using a single magnetic component as shown in Figure 4.

[0213] Using disposable laboratory pipettes, approximately 1 ml of each UV-Vis radiation-curable coating composition from Table 1 was independently applied in lines (approximately 25 mm in length). Then, using a K-Control Coater Model 101 equipped with a closed K-bar HC 3 (approximately 24 μm thick wet deposit) and K Paint Applicator (RK PRINTCOAT INSTRUMENTS) (speed 3), the five UV-Vis radiation-curable coating compositions were simultaneously and semi-automatically drawn.

[0214] A substrate bearing an application layer made from one of the five UV-Vis radiation-curable coating compositions listed in Table 1 is disposed on the magnetic assembly described herein and schematically shown in Figure 4. The magnetic assembly comprises a non-magnetic holder and four dipole magnets. Each of the four dipole magnets has the following dimensions: length L4 of 30 mm, width L5 of 24 mm, and thickness L6 of 8.5 mm (NdFeB magnets produced by molding and bonded to plastic, from Bomatec AG, CH-8181). (BMNpi-80 / 48 mold). Each of the four dipole magnets has a magnetic axis that is substantially parallel to its width and substantially parallel to the surface of the substrate. The four dipole magnets are arranged side by side in a non-magnetic retainer, their magnetic axes being parallel to each other and their north poles pointing in the same direction. The non-magnetic retainer has the following dimensions: length L1 of 140 mm, width L2 of 60 mm, and thickness L3 of 17.95 mm, and is made of polyphenylene sulfide (PPS). The upper surface of the retainer (i.e., the surface facing the substrate) is curved to be flush with the surface of the magnetic cylinder when arranged on it.

[0215] The distance (d) between the top surface of the dipole magnet and the top surface of the non-magnetic retainer (which also corresponds to the distance between the top surface of the dipole magnet and the substrate) is 3.35 mm.

[0216] The layer containing pigment particles was then exposed to cure by using an Fe-doped Hg lamp (150 W / cm from IST; passing twice at 100 m / min), which simultaneously with the orientation step (i.e., while the substrate bearing the coating made of the five UV-Vis radiation-curable coating compositions was still in the magnetic field), thus fixing the magnetic orientation pattern of the magnetic pigment particles obtained in this way.

[0217] The OEL thus obtained in Examples E1-E2 and Comparative Examples C1-C3 is shown in Figure 1 In the middle. For example Figure 1As shown, OEL E1-E2 and C2-C3 are well-defined, exhibiting a striking effect and displaying bright and sharp lines, while OEL C1 is blurry and not well-defined. Figure 1 As shown, the comparative composition C1, known to produce a safety feature containing a leafing pigment, is not suitable for producing an OEL, and no further evaluation of C1 has been conducted.

[0218] Second group of samples

[0219] The UV-Vis radiation-curable coating compositions E1-E2 and C2-C3 of Table 1 were independently applied to white trust paper (6cm × 6cm, from Louisenthal) (x20). The application was carried out by manual screen printing using a 90T screen to form a coating with a thickness of about 20μm and a shape of a disc surrounded by six circles, the shape having the following overall dimensions: 30mm × 22mm.

[0220] The substrate bearing the coating made of UV-Vis radiation-curable coating composition is independently placed on a dipole magnet (a plastic-bonded NdFeB magnet produced by molding, from Bomatec AG, CH-8181). On the BMNpi-80 / 48 mold, the dipole magnet has the following dimensions: length 30mm × width 24mm × thickness 8.5mm, and has a magnetic axis parallel to the surface of the substrate. The layer containing pigment particles is then exposed for curing by using an Fe-doped Hg lamp (150W / cm from IST; passing twice at a speed of 100m / min), and the magnetic orientation pattern of the magnetic pigment particles thus obtained is fixed simultaneously with the orientation step (i.e., while the substrate carrying the corresponding coating is still in the magnetic field).

[0221] The OELs thus obtained in Examples E1 and E2 and Comparative Examples C2-C3 are highly dynamic, exhibiting well-defined and striking effects, and displaying bright and sharp lines that move up and down when the OEL is tilted. The OEL of Comparative Example C1 is not well-defined and does not display sharp lines.

[0222] Mechanical resistance test: Drying wrinkling test ( Figure 2 )

[0223] Each sample prepared from compositions E1-E2 and C2-C3 was independently subjected to a drying wrinkling test using an IGT NBS wrinkling apparatus from IGT Testing Systems, according to the following method.

[0224] Each sample is independently wound along one edge, with the OEL facing inwards. The resulting roll is introduced into a crease apparatus, and the plunger of the apparatus is introduced. The sample is removed from the apparatus, unwound, and the process is repeated along the other three sides of the substrate.

[0225] The OEL produced by Example E1 was rated as excellent, meaning that no significant visible changes were observed, and the OEL remained intact after testing, with no substrate defects observed within the layer. Figure 2 The OEL rating of the sample prepared by Example E2 is good, meaning that only slight damage to the layer was observed. The OEL rating of the samples prepared by Comparative Examples C2-C3 is poor, meaning that considerable damage to the layer was observed.

[0226] Mechanical resistance testing: Washing machine test ( Figure 3 )

[0227] Each sample made from compositions E1-E2 and C2 was tested in a washing machine according to the following method. C1 and C3 were not evaluated because they failed in at least one of the previous tests.

[0228] Each sample was individually inserted into a washing glove and secured with two pins. The washing gloves containing the samples were then washed in a washing machine at 60°C with phosphate-free detergent for 1.5 hours (rotary drying at 800 rpm). The samples were then removed from the washing gloves and dried in an oven at 60°C between two glass plates for 1 hour.

[0229] The OEL ratings of the samples prepared from Examples E1-E2 were good, meaning that only minor damage to the layer was observed. The OEL rating of the sample prepared from Comparative Example C2 was poor, meaning that considerable damage to the layer was observed. Figure 3 ).

Claims

1. A UV-Vis radiation curable coating composition for producing an optical effect layer (OEL), the composition comprising: i) optionally one or more (meth)acrylate oligomers in a total amount of between about 0 wt.% and about 10 wt.%, preferably between about 1 wt.% and about 10 wt.%; ii) one or more (meth)acrylate monomers, preferably selected from the group consisting of tri(meth)acrylates, tetra(meth)acrylates, and mixtures thereof, in a total amount of between about 1 wt.% and about 20 wt.%, wherein the monomers are different from the (meth)acrylate oligomers of i); iii) one or more cyclic ether compounds, preferably selected from the group consisting of epoxides, oxetanes, and mixtures thereof, more preferably cycloaliphatic epoxides, oxetanes, and mixtures thereof, in a total amount of between about 5 wt.% and about 40 wt.%; iv) one or more vinyl ether compounds in a total amount of between about 10 wt.% and about 50 wt.%; v) one or more onium photoinitiators in a total amount of between about 0.1 wt.% and about 10 wt.%; vi) one or more photoinitiators selected from the group consisting of alkoxy ketones, phenylacetophenones, benzophenones, ketone sulfoxides, benzyl ketals, benzoin ethers, phosphine oxides, phenylglyoxalates, coumarins, camphorquinones, and mixtures thereof, in a total amount of between about 0.1 wt.% and about 10 wt.%; vii) one or more thermoplastic polymers in a total amount of between about 1 wt.% and about 20 wt.%; and viii) non-spherical magnetic or magnetizable pigment particles in a total amount of between about 1 wt.% and about 40 wt.%, weight percentages based on the total weight of the UV-Vis radiation curable coating composition.

2. The UV-Vis radiation curable coating composition according to claim 1, wherein the one or more (meth)acrylate oligomers i) are present in a total amount of between about 2 wt.% and 5 wt.%; the one or more (meth)acrylate monomers ii) are present in a total amount of between about 2 wt.% and 15 wt.%; the one or more cyclic ether compounds iii) are present in a total amount of between about 10 wt.% and 35 wt.%; the one or more vinyl ether compounds iv) are present in a total amount of between about 15 wt.% and 40 wt.%; the one or more onium photoinitiators v) are present in a total amount of between about 1 wt.% and 5 wt.%; the one or more photoinitiators vi) are present in a total amount of between about 1 wt.% and 5 wt.%; the one or more thermoplastic polymers vii) are present in a total amount of between about 3 wt.% and 15 wt.%; and the non-spherical magnetic or magnetizable pigment particles viii) are present in a total amount of between about 3 wt.% and 35 wt.%; weight percentages based on the total weight of the UV-Vis radiation curable coating composition.

3. The UV-Vis radiation curable coating composition according to claim 1 or 2, wherein at least one of the one or more thermoplastic polymers is polyvinyl butyral (PVB) and / or polyvinyl chloride (PVC).

4. The UV-Vis radiation curable coating composition according to any one of claims 1 to 3, wherein the non-spherical magnetic or magnetizable pigment particles are non-spherical optically variable magnetic or magnetizable pigment particles, preferably wherein the non-spherical optically variable magnetic or magnetizable pigment particles are selected from the group consisting of magnetic thin-film interference pigment particles, magnetic cholesteric liquid crystal pigment particles, interference-coated pigment particles comprising a magnetic material, and mixtures of two or more thereof.

5. The UV-Vis radiation curable coating composition according to any one of claims 1 to 4, further comprising about 0.1 wt.% to about 5 wt.% of one or more photoinitiators, the weight percent being based on the total weight of the UV-Vis radiation curable coating composition.

6. The UV-Vis radiation curable coating composition according to any one of claims 1 to 5, further comprising about 0.1 wt.% to about 10 wt.% of one or more fillers or extenders, the weight percent being based on the total weight of the UV-Vis radiation curable coating composition.

7. The UV-Vis radiation curable coating composition according to any one of claims 1 to 6, further comprising about 0.1 wt.% to about 10 wt.% of one or more UV stabilizers, the weight percent being based on the total weight of the UV-Vis radiation curable coating composition.

8. The UV-Vis radiation curable coating composition according to any one of claims 1 to 7, further comprising about 0.05 wt.% to about 5 wt.% of one or more color constant colorant components, the weight percent being based on the total weight of the UV-Vis radiation curable coating composition.

9. The UV-Vis radiation curable coating composition according to any one of claims 1 to 8, further comprising one or more marker substances or tracers and / or one or more machine readable materials.

10. The UV-Vis radiation curable coating composition according to any one of claims 1 to 9, further comprising one or more solvents in a total amount of less than 15 wt.%, the weight percent being based on the total weight of the UV-Vis radiation curable coating composition.

11. The UV-Vis radiation curable coating composition according to any one of claims 1 to 10, further comprising one or more additives selected from the group consisting of thickeners, surfactants, anti-settling agents, plasticizers, antifoams, waxes, and mixtures thereof.

12. A method for producing an optical effect layer (OEL) comprising the following steps: a) applying the UV-Vis radiation curable coating composition according to any one of claims 1 to 11 on a substrate to form a coating layer, b) exposing the coating in the first state to a magnetic field of a magnetic field generating device, thereby orienting at least a portion of the non-spherical magnetic or magnetizable pigment particles, c) hardening the coating to a second state to fix the non-spherical magnetic or magnetizable pigment particles in the position and orientation they have assumed.

13. The method according to claim 12, wherein the hardening step c) is carried out partly simultaneously with step b).

14. The method according to claim 12 or 13, wherein, step b) of exposing the coating to a magnetic field of a magnetic field generating device is carried out to uniaxially orient at least a portion of the non-spherical magnetic or magnetizable pigment particles, or wherein the non-spherical magnetic or magnetizable pigment particles are platelet-shaped magnetic or magnetizable pigment particles, and wherein step b) of exposing the coating to a magnetic field of a magnetic field generating device is carried out to biaxially orient at least a portion of the platelet-shaped magnetic or magnetizable pigment particles, or wherein the non-spherical magnetic or magnetizable pigment particles are platelet-shaped magnetic or magnetizable pigment particles, and wherein step b) of exposing the coating to a magnetic field of a magnetic field generating device consists of two steps, a first step comprising exposing the coating to a magnetic field of a magnetic field generating device to biaxially orient at least a portion of the platelet-shaped magnetic or magnetizable pigment particles, and a second step comprising exposing the coating to a magnetic field of a second magnetic field generating device to uniaxially orient at least a portion of the platelet-shaped magnetic or magnetizable particles, wherein the second step is carried out partly simultaneously, simultaneously or subsequently with respect to the first step.

15. The method according to any one of claims 12 to 14, wherein step a) of applying the UV-Vis radiation-curable coating composition is carried out by a method selected from the group consisting of screen printing, rotogravure printing, pad printing and flexographic printing.

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