Security ink compositions and machine-readable security features derived therefrom - Patent Application 20070122997

Abstract

At least one non-emissive undoped Y3Fe 5-x M x O 12 1. A security ink composition comprising a system pigment, wherein x satisfies the condition 0≦x≦1.25, and M is selected from the group consisting of aluminum, gallium, or calcium, and mixtures thereof, wherein at least one applied, preferably printed, machine-readable security feature derived from said security ink composition has, after drying and / or curing, a density of at least about 200×10 -12 m 3 and exhibiting a ferromagnetic resonance (FMR) signature for authentication purposes. A method for authenticating a machine-readable security feature derived from the security ink composition.

Description

Detailed Description of the Invention

[0001]

[0001] The present invention relates to the field of ferromagnetic security inks suitable for printing detectable, machine-readable security features on substrates, in particular security documents and / or articles.

[0002] [Background technology]

[0002] With the quality of color copying and printing constantly improving, it has been conventional practice to incorporate various security features into security documents such as banknotes, value documents or cards, transportation tickets or cards, tax stamps, and product labels, which are reproducibly ineffective against counterfeiting, tampering, or unauthorized duplication.

[0003]

[0003] For example, security features on security documents can be classified as "covert" and "overt" security features. The protection offered by covert security features relies on the notion that such features are hidden and typically require specialized equipment and knowledge for their detection, whereas "overt" security features are readily detectable by the naked human eye; for example, such features may be visible and / or detectable by touch while still being difficult to replicate and / or copy.

[0004]

[0004] Machine-readable security inks, such as magnetic inks, luminescent inks, and IR-absorbing inks, are widely used in the field of security documents, particularly banknote printing, to impart additional covert security features to security documents. The protection of security documents against counterfeiting and unauthorized duplication offered by covert security features relies on the notion that such features typically require specialized equipment and knowledge for their detection. In the field of security and the protection of valuable documents and valuable goods or articles against counterfeiting, tampering, and unauthorized duplication, it is known in the art to apply machine-readable security inks by a variety of printing processes, including printing processes using high-viscosity or paste-like inks, such as offset printing, letterpress printing, and intaglio printing (also known in the art as engraved steel die or copperplate printing), and liquid inks, such as rotogravure printing, flexography, screen printing, and inkjet printing.

[0005]

[0005] Magnetic detection methods are known in the art and provide covert detection of security documents and articles. Paramagnetic detection methods are described in WO 2020 / 245280, U.S. Pat. No. 4,376,264 or U.S. Pat. Appl. No. 2010 / 224,819. Another magnetic detection method relies on ESR / NMR detection techniques, e.g., U.S. Pat. No. 5,986,550. Magnetic resonance detection can be used for ferrimagnetic, ferromagnetic or paramagnetic security features.

[0006] Yet another magnetic detection method relies on ferromagnetism, which is the mechanism by which certain materials form permanent magnets or are attracted to magnets. It is well known in the art that ferromagnetism is the strongest type of magnetism, and ferromagnetic detection methods provide strong magnetic signals that can be used, for example, in ATMs or high-speed sorting (HSS) machines for fast and reliable magnetic detection.

[0007] In comparison, paramagnetic species typically provide low-intensity signals and require higher B-fields and excitation frequencies at higher concentrations. Therefore, paramagnetic species must be included in security ink compositions in fairly large quantities. This can lead to non-uniformity issues and additional costs. Because NMR detection requires complex equipment and processes, its integration into ATMs and HSS machines is impractical. Therefore, ferromagnetic detection methods and security features based on ferromagnetic detection methods provide practical and efficient detection and authentication services for security documents and / or articles.

[0008] Furthermore, modern machine-readable security features do not rely solely on one particular security feature. Rather, it is common, and indeed preferred, to incorporate multiple covert and / or overt security features to make the security features difficult to counterfeit. Another advantage is the possibility of having multiple authentication techniques that add layered or alternating covert and / or overt security features to a security document or article. With respect to detection and authentication, it is important that the multiple security features do not interfere with each other.

[0009]

[0009] However, some ferromagnetic components hinder the incorporation of other security features, particularly with regard to their underlying luminescence and / or IR absorption. This makes it difficult to include security features that are particularly luminescent and / or IR absorbing, since sensor technologies that identify said features will ultimately have interference from the ferromagnetic component itself. It is therefore desirable to incorporate ferromagnetic pigments that are non-luminescent and / or exhibit minimal or no IR absorption, while maintaining the possibility of reliably authenticating security documents and / or articles.

[0010]

[0010] Other aspects that need to be considered are the uniform incorporation of the ferromagnetic pigment in the ink composition, which provides stability and the ability to incorporate the pigment in a wide variety of ink compositions, and backward compatibility with standard magnetic readers. It is also desirable to provide the possibility of detection and authentication at low cost by using standard, off-the-shelf magnetic detection means and the ability to perform detection and authentication operations at a distance and at high speed.

[0011]

[0011] Therefore, there remains a need for stable and reliable security ink compositions that provide strong magnetic detection and authentication capabilities while minimizing interference with the incorporation of additional security features.

[0012] SUMMARY OF THE INVENTION It is therefore an object of the present invention to overcome the shortcomings of the prior art.

[0013] [Summary of the Invention] In one aspect, the present invention provides at least one non-emissive, undoped Y3Fe 5-x M x O 12 A security ink composition comprising a pigment of the type, x satisfies the condition 0≦x≦1.25, M is selected from the group consisting of aluminum, gallium, calcium, and mixtures thereof; and wherein the applied, preferably printed, at least one machine-readable security feature derived from said security ink composition has, after drying and / or curing, a density of at least about 200×10 -12 m 3 and exhibiting a ferromagnetic resonance (FMR) signature for authentication purposes. The present invention relates to a security ink composition.

[0014] In another aspect, the present invention relates to a machine-readable security feature comprising at least one security ink composition described herein.

[0015] In yet another aspect, the present invention relates to a security document or article that includes at least one machine-readable security feature as described herein.

[0016] In another aspect, the present invention is a method of authenticating a security document or article, comprising: a) providing a security document or article comprising at least one machine-readable security feature as described herein; b) defining at least one area of ​​said security document or article containing said at least one machine-readable security feature for purposes of FMR signal detection; c) detecting and recording an FMR spectrum of at least one machine-readable security feature to provide a recorded FMR spectrum including sufficient data points to establish at least one FMR signature; d) parameterizing or directly using the recorded FMR spectrum to establish a defined FMR signature in at least one region; e) comparing the FMR signature defined in the at least one established region from step d) with at least one predefined or expected FMR signature; f) determining the authenticity of the security document or article based on the comparison operation performed under step e); The present invention relates to a method comprising: [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 shows a parameterized FMR spectrum (ie, FMR signature) in terms of two parameters: linewidth (at half lobe) and line center field.

[0018] [Mode for Carrying Out the Invention] The following definitions may be used to interpret the meaning of terms set forth in the specification and / or claims.

[0019]

[0019] As used herein, the article "a" denotes one and more than one and does not necessarily restrict its referent to the singular.

[0020]

[0020] As used herein, the term "about" means that the quantity or value in question may be the specified value or some other value that is approximately the same. The phrase is intended to convey that similar values ​​within ±5% of the indicated value will promote the same results or effects according to the present invention.

[0021] As used herein, the term "and / or" or "or / and" means that all or only one of the elements of the group may be present. For example, "A and / or B" shall mean "only A, or only B, or both A and B."

[0022]

[0022] As used herein, the term "at least one" is meant to define one or more, for example, one or two or three.

[0023] The term "security document or article" generally refers to a document or article, respectively, that is protected against counterfeiting or fraud by at least one security feature. Examples of security documents include, but are not limited to, value documents and value commodities.

[0024] As used herein, the term "undoped" is meant to define the absence of elements from the lanthanide series of the periodic table. For clarity, the term absence does not exclude the unavoidable residual content of negligible amounts of lanthanide elements.

[0025]

[0025] As used herein, the term "non-emissive" is meant to define the absence of any kind of emission in the visible and IR ranges for the component so defined.

[0026] As used herein, a "ferromagnetic resonance (FMR) spectrum" is a recorded spectrum in at least one defined area of ​​a sample obtained after detection of a signal by a suitable magnetic detection means for at least one ferromagnetic pigment-containing security ink (composition) described herein. The spectrum may be recorded either at a given radio frequency in a magnetic field sweep or at a given magnetic field in a radio frequency sweep. The detection and recording of an FMR spectrum need not be performed over the entire possible range of the field or frequency sweep. Thus, it is also possible to record an FMR spectrum of a selected portion of the range, as long as the recorded spectrum provides sufficient data points to establish at least one FMR signature as described herein.

[0027] As used herein, a "ferromagnetic resonance (FMR) signature" is a characterization of a recorded FMR spectrum. The recorded FMR spectrum itself can be used directly for authentication purposes, i.e., the recorded spectrum can serve as an FMR signature. Alternatively, the FMR spectrum can be parameterized by at least one suitable method. In other words, the FMR spectrum can be used to establish at least one low-dimensional parametric representation derived from mathematical estimation of defined parameters from the FMR spectrum for authentication purposes. In one exemplary form, the FMR signature can be reduced to only two parameters: the linewidth and the line center field of the spectral mode. For more complex spectra, another suitable FMR signature can be obtained, for example, by projecting the spectrum onto a suitable functional basis (e.g., obtained by Gram-Schmidt orthogonalization of several spectra by principal component analysis). The established FMR signature, defined by at least one region, is either the FMR spectrum itself or any of its parameterized forms, and is a means of authentication for at least one machine-readable security feature, as described herein.

[0028] The security ink composition or security ink described herein comprises at least one non-emissive, undoped Y3Fe 5-x M x O 12 The pigment comprises a fluorine-based pigment, wherein x satisfies the condition 0≦x≦1.25, and M is selected from the group consisting of aluminum, gallium, or calcium, and mixtures thereof.

[0029]

[0029] YFe 5-x M x O 12Yttrium iron garnet pigments are also known in the art as yttrium iron garnet pigments, or YIG pigments. When the element M is present, the pigment can be correspondingly referred to as a YI(M)G pigment. As an example, when aluminum is present, the pigment is referred to as a YI(Al)G garnet pigment. YI(M)G pigments have a specific crystal structure assemblage that is influenced by the presence or absence of the element M. These variations in crystal structure impart different magnetic properties to the pigment depending on the values ​​of the elements M and x.

[0030] The element M may be freely selected from aluminum, gallium or calcium and mixtures thereof. The selection of the particular M element is dependent on the type of Y3Fe 5-x M x O 12 The addition of the element M does not significantly alter the detected ferromagnetic profile of the pigment, i.e., the pigment can provide, for authentication purposes, at least one characteristic and unique domain-defined FMR signature, regardless of the selected element M. In a preferred embodiment, the element M is aluminum.

[0031]

[0031] YFe 5-x M x O 12 The pigment may not contain the element M (x=0), but it is preferred that it contains at least some amount of the element M (value of x=0.01). Therefore, it is preferred to have at least some amount of Fe substituted with the element M in the crystal structure. Even small amounts of the element M substituting for the Fe ions in the pigment result in a good signal-to-noise ratio, making it easier to detect and authenticate the FMR signature defined in at least one area of ​​the applied, preferably printed, at least one machine-readable security feature.

[0032] In a preferred embodiment, YFe 5-x M x O 12The value of x in the system pigment is 0.01≦x≦1.25, more preferably 0.10≦x≦1.25. In an even more preferred embodiment, the value of x is in the range 0.25≦x≦1.00. The presence of element M within the above range provides an optimal signal-to-noise ratio and FMR detectability profile for the derived at least one machine-readable security feature.

[0033]

[0033] YFe 5-x M x O 12 The corresponding measure of substitution of Fe by element M in the pigment can also be described in terms of mole % substitution of Fe ions by those of element M in the crystal structure. As an example, if the value of x is 0.01, this corresponds to a 0.2 mole % substitution of Fe ions by those of element M in the pigment crystal structure. Considering the maximum value of x=1.25, this corresponds to a 25 mole % substitution of Fe ions. Thus, the described YFe 5-x M x O 12 In the M-based pigment, Fe ions can be substituted preferably up to 25 mol %. If the amount of Fe substituted by element M is high, the properties, particularly the integrated magnetic susceptibility, will decrease. In a preferred embodiment, the Fe substitution by element M is 2 mol % to 20 mol %, or 5 mol % to 20 mol %.

[0034]

[0034] YFe 5-x M x O 12 The system pigments may be incorporated into the security ink compositions described herein in amounts up to 40% by weight, up to 30% by weight, or preferably up to 20% by weight, or even up to 15% by weight. Due to the easy detectability of the described pigments, depending on the type of security ink formulated, only small amounts of the pigment may be sufficient to be included in the security ink composition.

[0035] Furthermore, the YFe 5-x M x O 12The use of the system pigments provides the flexibility to add other colored pigments and adjust the color profile of the security ink composition while maintaining detectability and authentication characteristics due to the pigments' own low inherent visible color.

[0036]

[0036] YFe 5-x M x O 12 The pigments can be obtained by synthesis methods known to those skilled in the art, such as mechanical alloying, co-precipitation in emulsion, solid-state sintering, spray pyrolysis, microwave hydrothermal synthesis and sol-gel synthesis. One of the commonly used synthesis methods is the calcination of the individual oxides at high temperatures.

[0037]

[0037] The security ink composition has a resolution of at least about 200 x 10 after drying and / or curing. -12 m 3 and is applied, preferably printed, to provide at least one machine-readable security feature exhibiting a ferromagnetic resonance (FMR) signature for authentication purposes.

[0038]

[0038] A minimum level of integrated magnetic susceptibility is important to ensure fast and reliable detection of security features, for example, in ATM or HSS machines, and to provide detectability by common magnetic detectors. When the value of x is within the previously defined range, the pigment provides the desired integrated magnetic susceptibility characteristics for detection of at least one printed machine-readable security feature while keeping the amount of pigment used at a fairly small level. This provides cost-saving and process efficiency advantages, especially compared to paramagnetic pigments. When x is >1.25, the integrated magnetic susceptibility may not be high enough to ensure reliable detection.

[0039]

[0039] Authentication of at least one machine-readable security feature comprising a security ink composition is performed by an FMR signature defined in at least one region. The FMR signature may take the form of the spectrum itself or may take at least one mathematically derived parameterized form. As described herein, for purposes of authentication of at least one machine-readable security feature comprising a single pigment or a blend of pigments, the established at least one region-defined FMR signature need not be identical or an exact match to at least one statistically expected or previously recorded FMR signature. As long as the at least one FMR signature meets an industry-accepted or minimum reliability / acceptance threshold, the at least one machine-readable security feature can be classified as authentic.

[0040] When a single pigment as described herein is included in a security ink composition, at least one specific unique FMR signature can be derived for the pigment from the recorded FMR spectrum, depending on the element M and its substitution amount. In one form, the FMR signature may be parameterized in terms of two parameters: line width and line center field. As an example, when the value of x is 1 and the element M is aluminum, Y3Fe 5-x M x O 12 The pigment has the formula Y3Fe4AlO 12It is possible to characterize this particular pigment, and thus the derived machine-readable security feature, in terms of at least one unique FMR signature defined by individual values ​​of line width and line center field. However, it should be noted that such parameterization represents only one way of establishing an FMR signature for authentication purposes. Other methods of parameterizing the recorded FMR spectrum can also be used; that is, depending on the parameterization method, more than two parameters may be derived to establish the FMR signature, or different parameterization methods may be used. It is also possible to use multiple parameterization methods in combination with each other. This makes it possible to develop a complex set of signatures for at least one machine-readable security feature, broadening the portfolio for authentication purposes.

[0041] In another embodiment, two pigments, i.e., a blend, as described herein may be included in a security ink composition. In such a case, the two pigments provide two individual FMR spectra. The two spectra may be combined into a common recorded FMR spectrum representing the blend of pigments. The characteristics of the individual FMR spectra of the mixture, and thus the common FMR spectrum, depend on the substitution element M, the amount of substitution x in each pigment, and the amount of pigment in the mixture. As described above for single pigments, the recorded common FMR spectrum itself or at least one parameterized form of the FMR spectrum can further be used. To the extent that the FMR signature of the blend differs from the signatures of the individual pigments, the FMR signature of the blend can serve as the basis for authentication purposes.

[0042] In yet another embodiment, an additional non-emissive, undoped Y3Fe, wherein x satisfies the condition 0≦x≦5, preferably 0≦x≦4.99, and M is selected from the group consisting of aluminum, gallium, or calcium, and mixtures thereof. 5-x M x O 12A system pigment may be included in the security ink composition, and the additional pigment also exhibits at least one specific FMR signature of the additional pigment itself, which is characteristic of the additional pigment. As mentioned above, it is also possible to derive at least one region-defined FMR signature for authentication purposes for such a blend.

[0043] YFe 5-x M x O 12 The pigments of this system can be incorporated into various ink compositions. Therefore, the pigments offer broad flexibility for incorporation into many types of ink compositions. Because the pigments provide a strong signal, they can be incorporated in smaller amounts without adversely affecting the uniformity and coatability of the security ink composition.

[0044]

[0044] Although it is possible to apply the security ink composition by processes other than printing (coating, spraying, extrusion, etc.), the security inks described herein are particularly suitable for application onto substrates such as those described herein by a printing process selected from the group consisting of an offset printing process, an intaglio printing process, a screen printing process, a rotogravure process, a flexographic printing process and an inkjet printing process, in particular flextensional inkjet printing, more preferably a printing process selected from the group consisting of an intaglio printing process and a screen printing process.

[0045] The security inks described herein may be oxidatively drying security inks, UV-Vis curable security inks, thermally drying security inks, or combinations thereof. However, one skilled in the art can fully incorporate the described pigments into other types of ink compositions.

[0046] Oxidatively drying security inks dry by oxidation in the presence of oxygen, particularly atmospheric oxygen. During the drying process, oxygen combines with one or more components of the ink, converting the ink to a solid state. The oxidatively drying Intaglio inks described herein contain one or more drying agents (also referred to in the art as catalysts, siccatives, siccative agents, desiccatives, or dessicators) to speed up the oxidation process. Examples of drying agents include inorganic or organic salts of metals, metal soaps of organic acids, metal complexes, and metal complex salts. Suitable salts of metals include salts containing cobalt, calcium, copper, zinc, iron, zirconium, manganese, barium, zinc, strontium, lithium, vanadium, and potassium as cations, and halides, nitrates, sulfates, carboxylates (e.g., acetates, ethylhexanoates, octanoates, and naphthenates) or acetoacetonates (e.g., ethylhexanoates of cobalt, manganese, and zirconium). Suitable examples of metal complexes and metal complex salts include manganese, vanadium, and iron compounds (i.e., manganese complexes, manganese complex salts, vanadium complexes, vanadium complex salts, iron complexes, and iron complex salts). When present, one or more driers used in the oxidatively dried Intaglio inks described herein are preferably present in a total amount of about 0.01% to about 10% by weight, more preferably about 0.1% to about 5% by weight, the weight percentages being based on the total weight of the oxidatively dried Intaglio ink.

[0047] Oxidative drying offset printing security inks are known in the art to require high viscosity. Typically, security inks suitable for oxidative drying offset printing processes require high viscosity at 40°C and 1000s. -1 The viscosity ranges from about 2.5 to about 25 Pa s, as measured on a Haake Roto-Visco RV1 with a 2 cm 0.5° cone.

[0048] As generally known in the art, oxidative drying security inks include one or more varnishes. The term "varnish" is also referred to in the art as a resin, binder, or ink vehicle. The drying varnish described herein is preferably present in the oxidative drying security ink described herein in an amount of about 10 to about 90% by weight, the weight percentage being based on the total weight of the oxidative drying security ink. The one or more varnishes for the oxidative drying security ink described herein are preferably selected from the group consisting of polymers containing unsaturated fatty acid residues, saturated fatty acid residues, and mixtures thereof, as generally known in the art. Preferably, the one or more varnished oxidative drying security inks described herein contain unsaturated fatty acid residues to ensure air-drying properties. Particularly preferred oxidative drying varnishes are resins containing unsaturated acid groups, and even more preferably resins containing unsaturated carboxylic acid groups. However, the resin may also contain saturated fatty acid residues. Preferably, the varnished oxidative drying security inks described herein contain acid groups, i.e., the oxidative drying varnish is selected from acid-modified resins. The oxidative drying varnishes described herein may be selected from the group consisting of alkyd resins, vinyl polymers, polyurethane resins, hyperbranched resins, rosin-modified maleic resins, rosin-modified phenolic resins, rosin esters, petroleum-resin-modified rosin esters, petroleum-resin-modified alkyd resins, alkyd-resin-modified rosin / phenolic resins, alkyd-resin-modified rosin esters, acrylic-modified rosin / phenolic resins, acrylic-modified rosin esters, urethane-modified rosin / phenolic resins, urethane-modified rosin esters, urethane-modified alkyd resins, epoxy-modified rosin / phenolic resins, epoxy-modified alkyd resins, terpene resins, nitrocellulose resins, polyolefins, polyamides, acrylic resins, and combinations or mixtures thereof. Polymer and resin are used interchangeably herein.

[0049]

[0049] Saturated and unsaturated fatty acid compounds may be obtained from natural and / or artificial sources. Natural sources include animal and / or plant sources. Animal sources may include animal fat, butterfat, fish oil, lard, liver fat, tuna fish oil, sperm whale oil, and / or tallow oil. Plant sources may include oils such as vegetable oils and / or non-vegetable oils. Examples of vegetable oils include, but are not limited to, bitter melon, borage, calendula, canola, castor, china, coconut, conifer seed, corn, cottonseed, dehydrated castor, flaxseed, grape seed, Jacaranda mischimofolia seed, linseed oil, palm, palm kernel, peanut, pomegranate seed, rapeseed, safflower, trifoliate gourd, soybean, sunflower, tall, tuna, and wheat germ. Artificial sources include distilled tall oil and / or chemical or biochemical synthetic methods. Suitable fatty acids include myristoleic acid (C 14 H 26 O2, CAS number 544-64-9), palmitoleic acid (C 16 H 30 O2, CAS No. 373-49-9), oleic acid (C 18 H 34 O2, CAS No. 112-80-1), α-eleostearic acid (C 18 H 30 O2, CAS No. 506-23-0, licanic acid (C 18 H 28 O3, CAS No. 623-99-4), linoleic acid (C 18 H 32 O2, CAS number 60-33-3), linolenic acid (C 18 H 30 O2, CAS number 463-40-1), stearidonic acid (C 18 H 28 O2, CAS number 20290-75-9), arachidonic acid (C 20 H 32 O2, CAS number 506-32-1), ricinoleic acid (C 18 H 34 O3, CAS No. 141-22-0, erucic acid (C 22 H 42O2, CAS No. 112-86-7), gadoleic acid (C 20 H 38 O2, CAS number 29204-02-2), clupanodonic acid (C 22 H 34 O2, CAS number 24880-45-3), herring acid (C 24 H 36 O2, CAS No. 68378-49-4) and mixtures thereof. These fatty acids are usually used in the form of mixtures of fatty acids derived from natural or synthetic oils.

[0050] The oxidative drying security inks described herein may further comprise one or more antioxidants, such as those known to those skilled in the art. Suitable antioxidants include, but are not limited to, alkylphenols, hindered alkylphenols, alkylthiomethyl-phenols, eugenol, secondary amines, thioethers, phosphites, phosphonites, dithiocarbamates, gallates, malonates, propionates, acetates and other esters, carboxamides, hydroquinone, ascorbic acid, triazines, benzyl compounds, and tocopherols and analogous terpenes. Such antioxidants are commercially available, for example, from sources disclosed in WO 02 / 100960. Hindered alkylphenols are phenols having at least one or two alkyl groups ortho to the phenolic hydroxyl. One, and preferably both, alkyl groups ortho to the phenolic hydroxyl are preferably secondary or tertiary alkyl, most preferably tertiary alkyl, particularly tert-butyl, tert-amyl, or 1,1,3,3-tetramethylbutyl. Preferred antioxidants are hindered alkylphenols, particularly 2-tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, 2-tert-butyl-p-cresol, and 2,6-di-tert-butyl-p-cresol. When present, the one or more antioxidants are present in an amount of about 0.05 to about 3 weight percent, the weight percent being based on the total weight of the oxidatively dried security ink.

[0051] The oxidative drying security inks described herein may further comprise one or more waxes, preferably selected from the group consisting of synthetic waxes, petroleum waxes, and natural waxes. Preferably, the one or more waxes are selected from the group consisting of microcrystalline wax, paraffin wax, polyethylene wax, fluorocarbon wax, polytetrafluoroethylene wax, Fischer-Tropsch wax, silicone fluid, beeswax, candelilla wax, montan wax, carnauba wax, and mixtures thereof. When present, the one or more waxes are present in an amount of about 0.1 to about 15 weight percent, the weight percent being based on the total weight of the oxidative drying security ink.

[0052]

[0052] According to one embodiment, the oxidative drying security ink described herein is an oxidative drying intaglio printing security ink, said oxidative drying intaglio printing security ink comprising one or more driers described herein, one or more varnishes described herein, and any additives or components described herein.

[0053]

[0053] At least one machine-readable security feature described herein may be preferably prepared by an intaglio printing process (also known in the art as engraved copperplate printing and engraved steel die printing), which allows for the deposition of a sufficiently large amount of machine-readable material on a substrate to enable detection and sensing. The intaglio printing process refers to a printing method used particularly in the field of security documents. The intaglio printing process is known to be the most consistent and high-quality printing process for producing fine tapered lines and is therefore the printing technique of choice for fine designs in the field of security documents, particularly banknotes and stamps. In particular, one of the notable features of the intaglio printing process is that the layer thickness of the ink transferred to the substrate can be varied from a few micrometers to tens of micrometers by using corresponding shallow or deep engravings on the intaglio printing device. As mentioned above, the layer thickness of the intaglio-printed security feature therefore allows for a sufficiently large amount of machine-readable material on the substrate for detection and sensing.

[0054] Intaglio inks, or more specifically oxidatively drying Intaglio security inks, are known in the art as requiring high viscosities. Typically, security inks suitable for the (oxidatively drying) Intaglio printing process are measured at 40°C and 1000 s using a Haake Roto-Visco RV1 rotational rheometer with a 25 μm truncated cone-plate of 20 mm diameter and 0.5° geometry. -1 It has a viscosity in the range of about 3 to about 60 Pa s.

[0055] The oxidatively drying Intaglio printing security inks described herein may further comprise one or more surfactants, in particular hydrophilic polymeric surfactants such as those described in EP 0 340 163. The role of any surfactant is to help wipe off excess ink present on the printing cylinder just before the printing cylinder is brought into contact with the substrate. This process of wiping off excess ink is part of any high-speed industrial Intaglio printing process and is carried out using tissue or paper rolls ("calico"), or a polymer wiping cylinder and an aqueous cleaning solution ("wiping solution"). In this case, the optional surfactant is used to emulsify the excess ink in the cleansing solution. The surfactant may be a nonionic, anionic, or cationic surfactant, as well as a zwitterionic surfactant. In the case of hydrophilic polymeric surfactants, the functional groups may be, for example, carboxylic or sulfonic acid groups, hydroxyl groups, ether groups, or primary, secondary, tertiary, or quaternary amino groups. The acid groups may be neutralized with amines, alkanolamines, or preferably inorganic bases, or combinations thereof. The primary, secondary and tertiary amino groups may be neutralized with inorganic or organic acids such as sulfonic acid, formic acid, acetic acid, trifluoroacetic acid, etc. Anionic polymeric surfactants (AMS) such as those described in EP 2014729 are particularly preferred.

[0056]

[0056] The UV-Vis curable security ink comprises a security ink that can be cured with UV-visible radiation. The UV-Vis curable security ink described herein comprises from about 0.1 wt % to about 20 wt % of one or more photoinitiators, preferably from about 1 wt % to about 15 wt %, the weight percentages being based on the total weight of the UV-Vis curable security ink.

[0057] Preferably, the UV-Vis curable security inks described herein comprise one or more UV-curable compounds that are monomers and oligomers selected from the group consisting of radically curable compounds and cationically curable compounds. The security inks described herein may be hybrid systems and may comprise a mixture of one or more cationically curable compounds and one or more radically curable compounds. Cationically curable compounds are typically cured by a cationic mechanism involving activation by radiation of one or more photoinitiators to liberate cationic species, such as acids, which then initiate curing to react and / or crosslink the monomers and / or oligomers, thereby curing the security ink. Radical-curable compounds are typically cured by a free-radical mechanism involving activation by radiation of one or more photoinitiators to generate radicals, which then initiate polymerization to cure the security ink.

[0058] Preferably, the UV-Vis curable security inks described herein comprise one or more oligomers (also referred to in the art as prepolymers) selected from the group consisting of oligomeric (meth)acrylates, vinyl ethers, propenyl ethers, cyclic ethers such as epoxides, oxetanes, tetrahydrofuran, lactones, cyclic thioethers, vinyl and propenyl thioethers, hydroxyl-containing compounds, and mixtures thereof. More preferably, the binder of the UV-Vis curable security inks described herein is prepared from an oligomer selected from the group consisting of oligomeric (meth)acrylates, vinyl ethers, propenyl ethers, cyclic ethers such as epoxides, oxetanes, tetrahydrofuran, lactones, and mixtures thereof. Typical examples of epoxides include, but are not limited to, glycidyl ethers, β-methylglycidyl ethers of aliphatic or cycloaliphatic diols or polyols, glycidyl ethers of diphenols and polyphenols, glycidyl esters of polyhydric phenols, 1,4-butanediol diglycidyl ether of phenol formaldehyde novolac, resorcinol diglycidyl ether, alkyl glycidyl ethers, glycidyl ethers including copolymers of acrylic acid esters (e.g., styrene-glycidyl methacrylate or methyl methacrylate-glycidyl acrylate), polyfunctional liquid and solid novolac glycidyl ether resins, polyglycidyl ethers and poly(β-methylglycidyl) ethers, poly(N-glycidyl) compounds, poly(S-glycidyl) compounds, epoxy resins in which the glycidyl or β-methylglycidyl groups are bonded to different types of heteroatoms, glycidyl esters of carboxylic and polycarboxylic acids, limonene monoxide, epoxidized soybean oil, bisphenol A and bisphenol F epoxy resins. Examples of suitable epoxides are disclosed in EP 2125713. Suitable examples of aromatic, aliphatic or alicyclic vinyl ethers include, but are not limited to, compounds having at least one, preferably at least two vinyl ether groups in the molecule.Examples of vinyl ethers include triethylene glycol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether, 4-hydroxybutyl vinyl ether, propenyl ether of propylene carbonate, dodecyl vinyl ether, tert-butyl vinyl ether, tert-amyl vinyl ether, cyclohexyl vinyl ether, 2-ethylhexyl vinyl ether, ethylene glycol monovinyl ether, butanediol monovinyl ether, hexanediol monovinyl ether, 1,4-cyclohexanedimethanol monovinyl ether, diethylene glycol monovinyl ether, ethylene glycol divinyl ether, and ethylene glycol butyl Examples of suitable vinyl ethers include, but are not limited to, vinyl ether, butane-1,4-diol divinyl ether, hexanediol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, triethylene glycol methyl vinyl ether, tetraethylene glycol divinyl ether, Pluriol-E-200 divinyl ether, polytetrahydrofuran divinyl ether-290, trimethylolpropane trivinyl ether, dipropylene glycol divinyl ether, octadecyl vinyl ether, (4-cyclohexyl-methyleneoxyethene)-glutaric acid methyl ester, and (4-butoxyethene)-isophthalic acid ester. Examples of hydroxy-containing compounds include, but are not limited to, polyester polyols such as polycaprolactone or polyester adipate polyols, glycols and polyether polyols, castor oil, hydroxy-functional vinyl and acrylic resins, cellulose esters such as cellulose acetate butyrate, and phenoxy resins. Further examples of suitable cationically curable compounds are disclosed in EP 2125713 and EP 0119425.

[0059] According to one embodiment of the present invention, the UV-Vis curable security ink described herein comprises one or more radically curable oligomeric compounds selected from (meth)acrylates, preferably selected from the group consisting of epoxy (meth)acrylates, (meth)acrylated oils, polyester (meth)acrylates, aliphatic or aromatic urethane (meth)acrylates, silicone (meth)acrylates, amino (meth)acrylates, acrylic (meth)acrylates and mixtures thereof. The term "(meth)acrylate" in the context of the present invention refers to acrylates and the corresponding methacrylates. The components of the UV-Vis curable security inks described herein may be formulated with additional vinyl ethers and / or monomeric acrylates, such as trimethylolpropane triacrylate (TMPTA), pentaerythritol triacrylate (PTA), tripropylene glycol diacrylate (TPGDA), dipropylene glycol diacrylate (DPGDA), hexanediol diacrylate (HDDA) and their polyethoxylated equivalents, such as polyethoxylated trimethylolpropane triacrylate, polyethoxylated pentaerythritol triacrylate, polyethoxylated tripropylene glycol diacrylate, polyethoxylated dipropylene glycol diacrylate, and polyethoxylated hexanediol diacrylate.

[0060] Alternatively, the UV-Vis curable security inks described herein may be hybrid inks, prepared from a mixture of radically curable compounds and cationically curable compounds such as those described herein.

[0061] As noted above, UV-Vis curing of monomers and oligomers requires the presence of one or more photoinitiators and may be accomplished in several ways. As mentioned herein and known to those skilled in the art, the UV-Vis curable security inks described herein that are cured and hardened on a substrate include one or more photoinitiators, such as those described herein, optionally with one or more photosensitizers, where the one or more photoinitiators and any one or more photosensitizers are selected according to the absorption spectrum of the photoinitiator or photosensitizer or photoinitiator and photosensitizer, which correlates with the emission spectrum of the radiation source. Depending on the penetration of electromagnetic radiation through the substrate, curing of the security ink may be achieved by increasing the irradiation time. However, depending on the substrate material, the irradiation time is limited by the substrate material and its sensitivity to heat generated by the radiation source.

[0062] Depending on the monomer, oligomer, or prepolymer used in the UV-Vis curable security ink described herein, different photoinitiators may be used. Suitable examples of free radical photoinitiators are known to those skilled in the art and include, but are not limited to, acetophenone, benzophenone, benzil dimethyl ketal, α-aminoketones, α-hydroxyketones, phosphine oxides and phosphine oxide derivatives, and mixtures of two or more thereof. Suitable examples of cationic photoinitiators are known to those skilled in the art and include, but are not limited to, onium salts such as organic iodonium salts (e.g., diaryliodoinium salts), oxonium salts (e.g., triaryloxonium salts), and sulfonium salts (e.g., triarylsulfonium salts), and mixtures of two or more thereof. Other examples of useful photoinitiators can be found in standard textbooks such as "Chemistry & Technology of UV & EB Formulation for Coatings, Inks & Paints," Volume III, "Photoinitiators for Free Radical Cationic and Anionic Polymerization," 2nd edition, edited by G. Bradley, by JV Crivello & K. Dietliker, published in 1998 by John Wiley & Sons, associated with SITA Technology Limited. To achieve efficient curing, it may also be suitable to include a sensitizer with one or more photoinitiators. Typical examples of suitable photosensitizers include, but are not limited to, isopropylthioxanthone (ITX), 1-chloro-2-propoxythioxanthone (CPTX), 2-chlorothioxanthone (CTX), and 2,4-diethylthioxanthone (DETX), as well as mixtures of two or more thereof.

[0063]

[0063] The UV-Vis curable security ink described in this specification is preferably a UV-Vis curable offset printing security ink, a UV-Vis curable intaglio printing security ink, a UV-Vis curable screen printing security ink, a UV-Vis curable flexographic printing security ink, a UV-Vis curable rotogravure printing security ink or a UV-Vis curable inkjet printing security ink, in particular a flextensional inkjet printing security ink, more preferably a UV-Vis curable intaglio printing security ink, a UV-Vis curable screen printing security ink, a UV-Vis curable flexographic printing security ink, a UV-Vis curable rotogravure printing security ink or a UV-Vis curable flextensional inkjet printing security ink.

[0064]

[0064] According to one embodiment, the UV-Vis curable security ink described herein is a UV-Vis curable offset printed security ink, said UV-Vis curable offset printed security ink comprising one or more photoinitiators described herein, and one or more UV curable compounds being the monomers and oligomers described herein and any additives or components described herein.

[0065]

[0065] According to one embodiment, the UV-Vis curable security ink described herein is a UV-Vis curable intaglio printing security ink, said UV-Vis curable intaglio printing security ink comprising one or more photoinitiators as described herein and one or more UV curable compounds being the monomers and oligomers as described herein and any additives or components as described herein.

[0066] UV-Vis curable offset printing security inks are known in the art to require high viscosity. Typically, security inks suitable for UV-Vis curable printing processes require high viscosity at 40°C and 1000s. -1The viscosity ranges from about 2.5 to about 25 Pa s, as measured on a Haake Roto-Visco RV1 with a 2 cm 0.5° cone.

[0067] UV-Vis curable intaglio security inks are known in the art as requiring high viscosity. Typically, security inks suitable for the intaglio printing process are typically measured at 40°C and 1000 s using a Haake Roto-Visco RV1 rotational rheometer with a 25 μm truncated cone-plate of 20 mm diameter and 0.5° geometry. -1 It has a viscosity in the range of about 3 to about 60 Pa s.

[0068]

[0068] Examples of UV-Vis curable intaglio printing security inks are described in WO 2021 / 018771, the disclosure of which is incorporated herein by reference.

[0069]

[0069] According to one embodiment, the UV-Vis curable security ink described herein is a UV-Vis curable screen printed security ink, said UV-Vis curable screen printed security ink comprising one or more photoinitiators described herein and one or more UV curable compounds being the monomers and oligomers described herein and any additives or components described herein.

[0070]

[0070] Screen printing (also known in the art as silk-screen printing) is a stencil process in which ink is transferred to a surface through a stencil supported by a fine woven mesh of silk, synthetic fibers, or metal threads tightly stretched over a frame. The pores of the mesh are closed in the non-image areas and remain open in the image areas, and the image carrier is called the screen. Screen printing may be flatbed or rotary. During printing, the frame is supplied with ink, the ink floods onto the screen, and then a squeegee is pulled across the screen, thus forcing the ink through the open pores of the screen. At the same time, the surface to be printed is held in contact with the screen and the ink is transferred to the screen. Screen printing is described, for example, in The Printing ink manual, R.H.Leach and R.J.Pierce, Springer Edition, 5 th Edition, pages 58-62 and Printing Technology, JMAdams and PADolin, Delmar Thomson Learning, 5 th Edition, pages 293-328.

[0071] Screen printing, or specifically UV-Vis curable screen printing security inks, are known in the art to require low viscosity. Typically, security inks suitable for screen printing processes have a viscosity in the range of about 0.05 to about 5 Pa s at 25° C. using a Brookfield machine (Model “DV-I Prime,” small sample adapter, spindle S27 (100 or 50 rpm)).

[0072]

[0072] Various types of suitable screen printing ink compositions are described in WO 2021 / 175907 and WO 2020 / 169316, the disclosures of which are incorporated herein by reference. Particularly suitable screen printing ink compositions are based on a hybrid (cationic / radical), radical cure mechanism and solvent-based.

[0073]

[0073] According to one embodiment, the UV-Vis curable security ink described herein is a UV-Vis curable flexographic security ink, said UV-Vis curable flexographic security ink comprising one or more photoinitiators described herein and one or more UV curable compounds being the monomers and oligomers described herein and any additives or components described herein.

[0074]

[0074] The flexographic printing method preferably uses a unit with a chambered doctor blade, an anilox roller, and a plate cylinder. The anilox roller preferably has small cells whose volume and / or density determine the protective varnish application speed. The chambered doctor blade contacts the anilox roller, filling the cells and simultaneously scraping off excess protective varnish. The anilox roller transfers the ink to the plate cylinder, which ultimately transfers the ink to the substrate. The plate cylinder can be made of a polymer or elastomeric material. Polymers are primarily used as photopolymers in plates and, in some cases, as seamless coatings on sleeves. Photopolymer plates are made from photosensitive polymers that are cured by ultraviolet (UV) light. The photopolymer plate is cut to the required size and placed in a UV light exposure unit. One side of the plate is fully exposed to UV light to harden or cure the base of the plate. The plate is then flipped over, a negative of the job is placed on the uncured side, and the plate is further exposed to UV light. This hardens the plate in the image areas. The plate is then treated to remove the uncured photopolymer from the non-image areas, which lowers the plate surface in these non-image areas. After treatment, the plate is dried and a post-exposure dose of UV light is applied to harden the entire plate. The preparation of plate cylinders for flexographic printing is described in "Printing Technology," J.M.A. Dams and P.A. Dolin, Delmar Thomson Learning, 5th Edition, pages 359-360.

[0075] UV-Vis curable flexographic security inks are known in the art to require low viscosity. Typically, security inks suitable for flexographic processes have a viscosity of 1000 s at 25°C using a TA Instruments DHR-2 rotational viscometer (cone face, 40 mm diameter). -1 It has a viscosity in the range of about 0.01 to about 1 Pa s.

[0076]

[0076] According to one embodiment, the UV-Vis curable security ink described herein is a UV-Vis curable rotogravure security ink, said UV-Vis curable rotogravure security ink comprising one or more photoinitiators described herein and one or more UV curable compounds being the monomers and oligomers described herein and any additives or components described herein.

[0077] As known to those skilled in the art, the term rotogravure refers to a printing process described, for example, in "Handbook of Print Media," Helmut Kipphan, Springer Edition, page 48. Rotogravure is a printing process in which image elements are engraved into the surface of a cylinder. Non-image areas remain at a constant, original level. Before printing, the entire printing plate (non-printing elements and printing elements) is inked and saturated with ink. Before printing, the ink is removed from the non-image by a wiper or blade, so that ink remains only in the cells. The image is transferred from the cells to the substrate by pressure, usually in the range of 2 to 4 bar, and by the adhesive forces between the substrate and the ink. The term rotogravure does not encompass, for example, intaglio printing processes (also known in the art as engraved steel die or copperplate printing processes), which rely on different types of ink.

[0078] UV-vis curable rotogravure security inks are known in the art to have low viscosity. Typically, security inks suitable for the rotogravure printing process have a viscosity of 0.01g at 25°C and 1000s using a TA Instruments rotational viscometer DHR-2 (cone face geometry, 40mm diameter). -1 It has a viscosity in the range of about 0.01 to about 0.5 Pa s.

[0079]

[0079] According to one embodiment, the UV-Vis curable security ink described herein is a UV-Vis curable flextensional inkjet printed security ink, said UV-Vis curable flextensional inkjet printed security ink comprising one or more photoinitiators described herein and one or more UV curable compounds being the monomers and oligomers described herein and any additives or components described herein.

[0080] Flextensional inkjet printing is inkjet printing using a flextensional inkjet printhead structure. A flextensional transducer typically includes a body or substrate, a flexible membrane having an orifice defined therein, and an actuator. The substrate defines a reservoir for holding a supply of flowable material, and the flexible membrane has a periphery supported by the substrate. The actuator may be piezoelectric (i.e., include a piezoelectric material that deforms when a voltage is applied), or may be thermally actuated, as described, for example, in U.S. Pat. No. 8,226,213. Thus, deformation of the actuator material deflects the flexible membrane, ejecting a quantity of flowable material from the reservoir through the orifice. U.S. Pat. No. 5,828,394 describes a flextensional printhead structure and discloses a fluid ejector including one wall including a thin, elastic membrane having an orifice defining a nozzle, and an element responsive to an electrical signal for deflecting the membrane to eject a droplet of fluid from the nozzle. U.S. Patent No. 6,394,363 describes a flextensional printhead structure, which uses excitation of a surface layer incorporating addressable nozzles arranged on one surface layer to form a liquid projection array capable of operating at high frequencies with a wide range of liquids. U.S. Patent No. 9,517,622 also describes a flextensional printhead structure, which describes a droplet forming device including a film member configured to vibrate to eject liquid held in a liquid holding unit, the film member having nozzles formed therein. The device further includes a vibration unit for vibrating the film member and a drive unit for selectively applying an ejection waveform and an agitation waveform to the vibration unit. U.S. Patent No. 8,226,213 also describes a flextensional printhead structure and a method for actuating a thermal bending actuator having an active beam fused to a passive beam. The method includes passing a current through the active beam to cause thermoelastic expansion of the active beam relative to the passive beam and bending of the actuator.

[0081] UV-Vis curable flextensional inkjet printing security inks are known in the art to have very low viscosities. Typically, security inks suitable for flextensional inkjet printing processes have a viscosity of 1000 s at 25°C and 1000 s using a TA Instruments rotational viscometer DHR-2 with a conical surface geometry and a diameter of 40 mm. -1 The viscosity of the composition is less than about 100 mPa s, as measured by .

[0082]

[0082] Thermally drying or heat-drying security inks comprise security inks that are dried by hot air, infrared radiation, or a combination thereof. Thermally drying security inks typically comprise from about 10% to about 90% by weight of solids that remain on the printed substrate and from about 10% to about 90% by weight of one or more solvents that evaporate as a result of drying, the one or more solvents being selected from the group consisting of organic solvents, water, and mixtures thereof.

[0083] Preferably, the organic solvents described herein are selected from the group consisting of alcohols (such as ethanol), ketones (such as methyl ethyl ketone), esters (such as ethyl acetate or propyl acetate), glycol ethers (such as DOWANOL™ DPM), glycol ether esters (such as butyl glycol acetate), and mixtures thereof.

[0084]

[0084] According to one embodiment, the heat-drying security ink described herein comprises a water-based heat-drying security ink comprising one or more resins selected from the group consisting of polyester resins, polyether resins, polyurethane resins (e.g., carboxylated polyurethane resins), polyurethane alkyd resins, polyurethane-acrylate resins, polyacrylate resins, polyether urethane resins, styrene acrylate resins, polyvinyl alcohol resins, poly(ethylene glycol) resins, polyvinylpyrrolidone resins, polyethyleneimine resins, modified starches, cellulose esters or ethers (such as cellulose acetate and carboxymethyl cellulose), copolymers and mixtures thereof.

[0085]

[0085] According to one embodiment, the heat-drying security ink described herein comprises a solvent-based heat-drying security ink comprising one or more resins selected from the group consisting of nitrocellulose, methylcellulose, ethylcellulose, cellulose acetate, polyvinyl butyral, polyurethane, polyacrylate, polyamide, polyester, polyvinyl acetate, rosin-modified phenolic resin, phenolic resin, maleic acid resin, styrene-acrylic resin, polyketone resin, and mixtures thereof.

[0086]

[0086] Suitable heat-drying security ink compositions are described in WO 2020 / 239740 and WO 2019 / 219250, the disclosures of which are incorporated herein by reference.

[0087]

[0087] As mentioned above, dual cure or dual curing security inks may be used to print at least one machine-readable security feature described herein, these security inks combining two drying or curing mechanisms.

[0088]

[0088] Examples of dual cure or double curing security inks include an oxidative drying mechanism and a UV-Vis curing mechanism, such as the intaglio security inks described in, for example, EP 2171007.

[0089]

[0089] Examples of dual cure or double cured security inks include oxidative and thermal drying mechanisms such as, for example, screen printed security inks, rotogravure printed security inks and flextensional ink jet printed security inks.

[0090] Examples of dual-cure or dual-cure security inks include UV-Vis curing and thermal drying mechanisms, such as screen-printed security inks and rotogravure inks. Typically, such dual-cure or dual-cure security inks are similar to UV-Vis curable security inks, but contain a volatile portion comprised of water and / or one or more organic solvents. These volatile components are first evaporated using hot air and / or IR dryers, and UV-Vis curing then completes the curing process. The compositions of such inks are described, for example, in WO 2019 / 002046.

[0091]

[0091] The security ink or security ink composition described herein may further comprise one or more fillers and / or extenders, preferably selected from the group consisting of talc, mica (e.g., muscovite), montmorillonite, bentonite, wollastonite, halloysite, calcined clay, kaolin, carbonates (e.g., calcium carbonate, magnesium carbonate), silicates (e.g., magnesium silicate, aluminum silicate), vermiculite, amorphous silica (e.g., fumed silica, precipitated silica, silica flour), wood flour (sawdust), natural fibers, synthetic fibers (such as carbon fibers or carbon nanotubes), and mixtures thereof, preferably selected from the group consisting of talc, mica, wollastonite, calcined clay, carbonates, amorphous silica, and mixtures thereof.

[0092] When present in an Intaglio ink, the one or more fillers or extenders are preferably present in a total amount of from about 0.1% to about 50% by weight, more preferably from about 20% to about 40% by weight, the weight percentages being based on the total weight of the oxidatively dried Intaglio ink. When present in a rotogravure, flexographic or screen printing ink, the one or more fillers or extenders are preferably present in a total amount of from about 0.05% to about 20% by weight, more preferably from about 0.1% to about 10% by weight, even more preferably from about 0.5% to about 5% by weight, the weight percentages being based on the total weight of the rotogravure, flexographic or screen printing ink.

[0093]

[0093] The security inks described herein may further comprise one or more coloring components selected from the group consisting of optically variable pigments, constant color pigments, constant color dyes and mixtures thereof, preferably selected from the group consisting of constant color organic pigments, constant color inorganic pigments and mixtures thereof.

[0094]

[0094] Dyes suitable for the security ink composition are known in the art and are preferably selected from the group comprising reactive dyes, direct dyes, anionic dyes, cationic dyes, acid dyes, basic dyes, food dyes, metal complex dyes, solvent dyes and mixtures thereof. Typical examples of suitable dyes include, but are not limited to, coumarin, cyanine, oxazine, uranine, phthalocyanine, indolinocyanine, triphenylmethane, naphthalocyanine, indo-naphthalometallic dyes, anthraquinone, anthrapyridone, azo dyes, rhodamine, squarylium dyes, and croconium dyes. Typical examples of dyes suitable for the present invention include CI Acid Yellow 1, 3, 5, 7, 11, 17, 19, 23, 25, 29, 36, 38, 40, 42, 44, 49, 54, 59, 61, 70, 72, 73, 75, 76, 78, 79, 98, 99, 110, 111, 121, 127, 131, 135, 142, 157, 162, 164, 165, 194, 204, 236, 245, CI Direct Yellow 1, 8, 11, 12, 24, 26, 27, 33, 39, 44, 50, 58, 85, 86, 87, 88, 89, 98, 106, 107, 110, 132, 142, 144, CI Basic Yellow 13, 28, 65, CI Reactive Yellow 1, 2, 3, 4, 6, 7, 11, 12, 13, 14, 15, 16, 17, 18, 22, 23, 24, 25, 26, 27, 37, 42, CI F CI Acid Yellow 3, 4, CI Acid Orange 1, 3, 7, 10, 20, 76, 142, 144, CI Basic Orange 1, 2, 59, CI Food Orange 2, CI Orange B, CI Acid Red 1, 4, 6, 8, 9, 13, 14, 18, 26, 27, 32, 35, 37, 42, 51, 52, 57, 73, 75, 77, 80, 82, 85, 87, 88, 89, 92, 94, 97, 106, 11 1, 114, 115, 117, 118, 119, 129, 130, 131, 133, 134, 138, 143, 145, 154, 155, 158, 168, 180, 183, 184, 186, 19 4, 198, 209, 211, 215, 219, 221, 249, 252, 254, 262, 265, 274, 282, 289, 303, 317, 320, 321, 322, 357, 359, CIBasic Red 1, 2, 14, 28, CI Direct Red 1, 2, 4, 9, 11, 13, 17, 20, 23, 24, 28, 31, 33, 37, 39, 44, 46, 62, 63, 75, 79, 80, 81, 83, 84, 89, 95, 99, 113, 197, 201, 218, 220, 224, 225, 226, 227, 228, 229, 230, 231, 253, CI Reactive Red 1, 2, 3, 4, 5, 6, 7, 8, 11, 12, 13, 15, 16, 17, 19, 20, 21, 22, 23, 24, 28, 29, 31, 32, 33 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 45, 46, 49, 50, 58, 59, 63, 64, 108, 180, CI Food Red 1, 7, 9, 14, CI Acid Blue 1, 7, 9, 15, 20, 22, 23, 25, 27, 29, 40, 41, 43, 45, 54, 59, 60, 62, 72, 74, 78, 80, 82, 83, 90, 92, 93, 100, 102, 103, 104, 112, 113, 117, 120, 126, 127, 129, 130, 131, 138, 140, 142, 143, 151, 154, 1 58, 161, 166, 167, 168, 170, 171, 182, 183, 184, 187, 192, 193, 199, 203, 204, 205, 229, 234, 236, 249, 254, 285, CI Basic Blue 1, 3, 5, 7, 8, 9, 11, 55, 81, CI Direct Blue 1, 2, 6, 15, 22, 25, 41, 71, 76, 77, 78, 80, 86, 87, 90, 98, 106, 108, 120, 123, 158, 160, 163, 165, 168, 192, 193, 194, 195, 196, 199, 200, 2 01, 202, 203, 207, 225, 226, 236, 237, 246, 248, 249, CI Reactive Blue 1, 2, 3, 4, 5, 7, 8, 9, 13, 14, 15, 17, 18, 19, 20, 21, 25, 26, 27, 28, 29, 31, 32, 33, 34, 37, 38, 39, 40, 41, 43, 44, 46, 77, CI Food Blue 1, 2, CI Acid Green 1, 3, 5, 16, 26, 104, CI Basic Green 1, 4, CI Food Green 3, CI Acid Violet 9, 17, 90, 102, 121, CIBasic Violet 2, 3, 10, 11, 21, CI Acid Brown 101, 103, 165, 266, 268, 355, 357, 365, 384, CI Basic Brown 1, CI Acid Black 1, 2, 7, 24, 26, 29, 31, 48, 50, 51, 52, 58, 60, 62, 63, 64, 67, 72, 76, 77, 94, 107, 108, 10 9, 110, 112, 115, 118, 119, 121, 122, 131, 132, 139, 140, 155, 156, 157, 158, 159, 191, 194, CI Direct Black 17, 19, 22, 32, 39, 51, 56, 62, 71, 74, 77, 94, 105, 106, 107, 108, 112, 113, 117, 118, 132, 133, 14 6, 154, 168, CI Reactive Black 1, 3, 4, 5, 6, 8, 9, 10, 12, 13, 14, 18, 31, CI Food Black 2, CI Solvent Yellow 19, CI Solvent Orange 45, CI Solvent Red 8, CI Solvent Green 7, CI Solvent Blue 7, CI Solvent Black 7, CI Disperse Yellow 3, CI Disperse Red 4, 60, CI Disperse Blue 3, and the metal azo dyes disclosed in U.S. Pat. Nos. 5,074,914, 5,997,622, 6,001,161, JP-A-02-080470, JP-A-62-190272, and JP-A-63-218766. Suitable dyes for the present invention may be infrared-absorbing or luminescent dyes. When present, the one or more dyes described herein are preferably present in a total amount of from about 1% to about 20% by weight, the weight percentage being based on the total weight of the security ink composition.

[0095] Typical examples of organic and inorganic pigments include CI Pigment Yellow 12, CI Pigment Yellow 42, CI Pigment Yellow 93, CI Pigment 109, CI Pigment Yellow 110, CI Pigment Yellow 147, CI Pigment Yellow 173, CI Pigment Orange 34, CI Pigment Orange 48, CI Pigment Orange 49, CI Pigment Orange 61, CI Pigment Orange 71, CI Pigment Orange 73, CI Pigment Red 9, CI Pigment Red 22, CI Pigment Red 23, CI Pigment Red 67, CI Pigment Red 122, CI Pigment Red 144, CI Pigment Red 146, CI Pigment Red 170, CI Pigment Red 177, CI Pigment Red 179, CI Pigment Red Pigment Red 185, CI Pigment Red 202, CI Pigment Red 224, CI Pigment Brown 6, CI Pigment Brown 7, CI Pigment Red 242, CI Pigment Red 254, CI Pigment Red 264, CI Pigment Brown 23, CI Pigment Blue 15, CI Pigment Blue 15:3, CI Pigment Blue 60, CI Pigment Violet 19, CI Pigment Violet 23, CI Pigment Violet 32, CI Pigment Violet 37, CI Pigment Green 7, CI Pigment Green 36, CI Pigment Black 7, CI Pigment Black 11, Pigment Black 31, Pigment Black 32, CI Pigment White 4, CI Pigment White 6, CI Pigment White 7, CI Pigment White 21, CIPigment White 22, antimony yellow, lead chromate, lead chromate sulfate, lead molybdate, ultramarine blue, cobalt blue, manganese blue, chromium oxide green, hydrated chromium oxide green, cobalt green, cerium sulfide, cadmium sulfide, cadmium sulfoselenide, zinc ferrite, bismuth vanadate, Prussian blue, mixed metal oxide, azo, azomethine, methine, anthraquinone, phthalocyanine, perinone, perylene, diketopyrrolopyrrole, thioindigo, thiadiindigo, dioxazine, iminoisoindoline, iminoisoindolinone, quinacridone, flavanthrone, indanthrone, anthrapyrimidine, and quinophthalone pigments. When present, the inorganic pigments, organic pigments, or mixtures thereof described herein are preferably present in a total amount of about 0.1 wt.% to about 45 wt.%, the weight percentage being based on the total weight of the security ink composition.

[0096] According to one aspect of the present invention, the security ink composition described herein is an optically variable ink and comprises an optically variable pigment or a mixture of different optically variable pigments. The optically variable ink may further comprise one or more constant color pigments. The optically variable ink preferably comprises an optically variable pigment or a mixture of different optically variable pigments, the optically variable pigment preferably being selected from the group consisting of thin film interference pigments, interference coated pigments, cholesteric liquid crystal pigments, and mixtures thereof. When present, the optically variable pigments described herein are comprised in a total amount of about 5% to about 40% by weight, more preferably about 10% to about 35% by weight, the weight percentages being based on the total weight of the security ink composition.

[0097] The security inks described herein may further comprise one or more machine-readable compounds known in the art. Such machine-readable compounds or taggants or markers may be included for forensic detection purposes. Various devices may be used to detect such machine-readable compounds, such as (FT)IR spectrometers, fluorometers / luminescence detectors, optical microscopes, scanning or tunneling electron microscopes, Raman spectrometers, etc.

[0098]

[0098] Suitable machine-readable IR absorbing compounds are described in WO 2019 / 002046, the disclosure of which is incorporated herein by reference.

[0099] Suitable machine-readable organic luminescent compounds are described in WO 2011 / 147587, WO 2012 / 160182, WO 2013 / 068324, WO 2013 / 068275, WO 2013 / 075980, WO 2013 / 079521, and inorganic luminescent compounds are described in WO 2014 / 048702, WO 2018 / 172318, WO 2009 / 006634, WO 2011 / 002960, WO 2011 / 041657. The above references are incorporated herein by reference.

[0100] Suitable machine-readable SERS compounds are described in U.S. Patent No. 5,609,907, WO 1998 / 010289, WO 2010 / 135354 and WO 2010 / 135351, the foregoing references being incorporated herein by reference.

[0101] Suitable machine-readable compounds having indicia that require a particular shape and / or magnification for viewing are described, for example, in U.S. Patent Application Publication No. 2012 / 107738, U.S. Patent Application Publication No. 2009 / 2017842, U.S. Patent Application Publication No. 2008 / 236447, U.S. Patent Application Publication No. 2008 / 107856, U.S. Patent Application Publication No. 2008 / 088895, U.S. Patent No. 7,639,109, U.S. Patent No. 7,241,489, U.S. Patent No. 7,645,510, and European Patent No. 1,741,757. The foregoing references are incorporated herein by reference.

[0102] The security inks 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 security ink, such as viscosity (e.g., anti-settling agents and plasticizers), foaming properties (e.g., defoamers and degassing agents), lubrication properties (waxes), UV stability (light stabilizers), adhesion properties, surface properties (wetting agents, oleophobic agents, and hydrophobic agents), and drying / curing properties (curing accelerators, sensitizers, crosslinkers). The additives described herein may be present in the security inks described herein in amounts and forms known in the art, including the form of so-called nanomaterials, in which at least one of the dimensions of the additive is in the range of 1 to 1000 nm.

[0103]

[0103] The present invention further provides a method for producing a security ink as described herein and a security ink obtained from the method. The security ink as described herein comprises at least one non-emissive, undoped Y3Fe as described herein. 5-x M x O 12 The security ink may be prepared by dispersing or mixing the system pigment and all other ingredients to form a liquid or paste-like ink. When the security ink described herein is an oxidatively drying Intaglio ink, one or more oxidative driers are typically added at the end of the dispersion process. When the security ink described herein is a UV-VIS curable security ink, one or more photoinitiators may be added to the composition during the dispersion or mixing step of all other ingredients, or at a later stage, i.e., after the formation of the liquid or paste-like ink. The varnishes, binder compounds, monomers, oligomers, resins, and additives are typically selected from those known in the art and those described above, and depend on the printing process used to apply the security ink described herein to the substrate described herein.

[0104]

[0104] The security inks described herein are applied onto the substrates described herein to produce at least one machine-readable security feature by coating, spraying, extrusion, or a mixture of these application techniques.

[0105]

[0105] In a preferred embodiment, a printing process is used for applying the security ink, preferably selected from the group consisting of an offset process, an intaglio printing process, a screen printing process, a rotogravure process, a flexographic printing process and an inkjet printing process, more preferably selected from the group consisting of an intaglio printing process, a screen printing process, a rotogravure process, a flexographic printing process and a flextensional inkjet printing process, even more preferably selected from the group consisting of an intaglio printing process, a screen printing process and a rotogravure process.

[0106]

[0106] The present invention further provides a method of producing at least one machine-readable security feature as described herein, the method comprising the step a) of applying a security ink as described herein onto a substrate as described herein, preferably by a printing process selected from the group consisting of intaglio printing, screen printing, flexography, rotogravure printing and inkjet printing.

[0107]

[0107] After step a), step b) is carried out of drying and / or curing the security ink in the presence of UV-VIS radiation and / or air or heat to form at least one machine-readable security feature as described herein on the substrate.

[0108]

[0108] The present invention further provides at least one machine-readable security feature made with the security ink described herein on a substrate described herein.

[0109]

[0109] The substrates described herein are preferably selected from the group consisting of paper or other fibrous materials such as cellulose (including woven and nonwoven fibrous materials), paper-containing materials, glass, metal, ceramic, plastics and polymers, metallized plastics or polymers, composite materials, and mixtures or combinations of two or more thereof. Typical paper, paper-like, or other fibrous materials are made from a variety of fibers, including, but not limited to, abaca, cotton, linen, wood pulp, and blends thereof. As is well known to those skilled in the art, cotton and cotton / linen blends are preferred for banknotes, while wood pulp is commonly used for non-banknote security documents. Typical examples of plastics and polymers include polyolefins such as polyethylene (PE) and polypropylene (PP), including biaxially oriented polypropylene (BOPP), polyamides, polyesters such as poly(ethylene terephthalate) (PET), poly(1,4-butylene terephthalate) (PBT), poly(ethylene 2,6-naphthoate) (PEN), and polyvinyl chloride (PVC). Spunbond olefin fibers, such as those sold under the Tyvek® trademark, may also be used as substrates. Typical examples of metallized plastics or polymers include the above-mentioned plastic or polymer materials having metals continuously or discontinuously disposed on the surface. 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 above-mentioned metals. Metallization of the above-mentioned plastic or polymer materials may be carried out by an electrodeposition process, a high-vacuum coating process, or a sputtering process. 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, as well as plastic and / or polymer fibers incorporated into paper-like or fibrous materials, such as those mentioned above. Naturally, the substrate may contain additional additives known to those skilled in the art, such as fillers, sizing agents, whiteners, processing aids, reinforcing agents, or wet strength agents.

[0110] The present invention further provides a security document comprising a substrate as described herein and at least one machine-readable security feature as described herein, or a security document comprising two or more of the at least one machine-readable security feature as described herein. Security documents include, but are not limited to, value documents and value items. Typical examples of value documents include, but are not limited to, banknotes, certificates, tickets, checks, vouchers, revenue stamps and tax labels, contracts, etc., and identity documents such as passports, identity cards, visas, driver's licenses, bank cards, credit cards, transaction cards, access documents or cards, admission tickets, public transport tickets, or title deeds. The term "value items" refers to packaging materials, particularly for the pharmaceutical, cosmetic, electronics, or food industries, that can be protected from counterfeiting and / or unauthorized duplication to ensure the contents of the package, such as, for example, authentic drugs. Examples of these packaging materials include, but are not limited to, labels such as authentication brand labels, tamper-evident labels, and seals. Preferably, the security documents described herein are selected from the group consisting of banknotes, identification cards, entitlement documents, driver's licenses, credit cards, access cards, transportation title deeds, vouchers, and secure product labels. Alternatively, the security features described herein may be produced on a secondary substrate, such as a security thread, security stripe, foil, decal, window, or label, and then transferred to the security document in a separate step. The above-mentioned substrates, value documents, and value items are exemplary and do not limit the scope of the present invention.

[0111]

[0111] For the purpose of further increasing the level of security and resistance of security documents to counterfeiting and unauthorized duplication, the substrates described herein may include printed, coated, or laser marked or laser perforated indicia, watermarks, security threads, fibers, planchets, luminescent compounds, windows, foils, decals, primers, and combinations of two or more thereof, provided that these potential additional elements do not adversely affect the magnetic detectability of the at least one applied, preferably printed, machine-readable security feature.

[0112]

[0112] One or more protective layers may be applied over at least one machine-readable security feature or security document described herein in order to enhance durability in terms of dirt or chemical resistance and cleanliness, and thus extend the circulation life of the security document, or to modify the aesthetic appearance (e.g., optical gloss) of the security document. If present, the one or more protective layers are usually made of a protective varnish, which may be clear or slightly pigmented or tinted, and may be more or less glossy. The protective varnish may be a radiation-curable composition, a heat-drying composition, or any combination thereof. Preferably, the one or more protective layers are made of a radiation-curable composition, more preferably a UV-Vis-curable composition.

[0113]

[0113] The at least one machine-readable security feature described herein may be provided directly on a substrate that will remain permanently (such as for banknote applications). Alternatively, the at least one machine-readable security feature may also be provided on a temporary substrate for production purposes, from which the at least one machine-readable security feature is subsequently removed. The temporary substrate may then be removed from the at least one machine-readable security feature after hardening / curing of the security ink described herein for production of the at least one machine-readable security feature.

[0114] Alternatively, in another embodiment, an adhesive layer may be present on at least one machine-readable security feature or on a substrate containing said machine-readable security feature, said adhesive layer being on the side of the substrate opposite to the side on which the machine-readable security feature is provided or on the same side as the machine-readable security feature and above the machine-readable security feature. Thus, an adhesive layer may be applied to the machine-readable security feature or the substrate, said adhesive layer being applied after a drying or curing step is completed. Such an article may be attached to any kind of document or other article or item without printing or other processes involving machines and without significant labor. Alternatively, the substrate described herein containing the machine-readable security feature described herein may be in the form of a transfer foil that can be applied to a document or article in a separate transfer step. For this purpose, the substrate is provided with a release coating on which the machine-readable security feature is generated as described herein. One or more adhesive layers may be applied on the dried machine-readable security feature thus generated.

[0115]

[0115] Also described herein are substrates, security documents, decorative elements and objects comprising two or more, i.e. two, three, four etc. at least one machine-readable security feature as described herein. Also described herein are articles, in particular security documents, decorative elements or objects, comprising at least one machine-readable security feature as described herein.

[0116]

[0116] As mentioned above, at least one machine-readable security feature described herein may be used to protect and authenticate a security document or decorative element.

[0117]

[0117] Typical examples of decorative elements or objects include, but are not limited to, luxury goods, cosmetic packaging, automotive parts, electronic / electrical equipment, furniture, and nail products.

[0118] At least one non-emissive undoped Y3Fe as described herein 5-x M x O 12 The at least one machine-readable security feature comprising the system pigment may consist of indium, which refers to a code (such as a barcode or QR code), a symbol, an alphanumeric symbol, a motif, a geometric pattern, a letter, a word, a number, a logo, a figure, a portrait, and combinations thereof.

[0119] According to one embodiment, the substrate, security document or article described herein comprises at least one non-emissive undoped Y3Fe 5-x M x O 12 The present invention also provides a combination security feature comprising a first region comprising at least one machine-readable security feature described herein derived from a security ink containing a non-luminescent, undoped pigment, and a second region in which the non-luminescent, undoped pigment is absent. The first and second regions may be adjacent, partially overlapping, or spaced apart. The first and second regions may comprise an image and may be made of ink containing one or more compounds (e.g., pigments or dyes) that absorb in the visible region of the electromagnetic spectrum, preferably selected so that both regions are color-matched in the visible spectrum.

[0120]

[0120] Another embodiment of the present invention is a method for authenticating a security document or article, comprising: a) providing a security document or article comprising at least one machine-readable security feature as described herein; b) defining at least one area of ​​said security document or article containing said at least one machine-readable security feature for purposes of FMR signal detection; c) detecting and recording an FMR spectrum of at least one machine-readable security feature to provide a recorded FMR spectrum including sufficient data points to establish at least one FMR signature; d) parameterizing or directly using the recorded FMR spectrum to establish a defined FMR signature in at least one region; e) comparing the FMR signature defined in the at least one established region from step d) with at least one predefined or expected FMR signature; f) determining the authenticity of the security document or article based on the comparison operation performed under step e); The present invention relates to a method comprising:

[0121]

[0121] A security document or article comprising at least one machine-readable security feature as described herein may comprise at least one non-luminescent undoped Y3Fe present in the machine-readable security feature. 5-x M x O 12 The ferromagnetic signal characteristics of the system pigment are detected. Detection is performed in a predefined area of ​​the security document or article, where a security ink composition is applied, preferably printed, to form a machine-readable security feature. To determine authenticity, at least one FMR signature defined in the defined area is compared to one expected in the defined area, but not in another area of ​​the security document or article. Thus, if the established FMR signature is not determined in the defined area or is observed in an undefined area, the sample is classified as inauthentic.

[0122]

[0122] FMR detection may be performed by systems based on known technology, such as off-the-shelf microwave electronics and permanent magnet arrangements. Specifically, detection may be performed by a frequency sweep with an IQ demodulator-based impedance measurement system with a fixed magnet, a locked oscillator-based detector with a fixed magnet, or a discrete matrix of fixed-frequency IQ demodulator-based impedance measurement systems with a fixed magnet. The use of other detection means is well within the understanding of those skilled in the art. The detected FMR signal may then be recorded and stored using computerized means.

[0123] After detection and recording of an FMR spectrum as described herein, an FMR signature defined by at least one region is derived from the recorded spectrum. As described herein, the spectrum itself or at least one suitable mathematically derived parameterized representation of the spectrum can be obtained. Thus, the FMR spectrum results in the generation of an FMR signature defined by at least one region in a suitable form for authentication purposes.

[0124] At least one non-emissive undoped Y3Fe 5-x M x O 12 For a particular machine-readable security feature resulting from a system pigment and a blend of the individual pigments contained in the security ink composition, it is possible to derive one or more statistically expected "reference" signatures to which the FMR signature defined in the established region can be compared. Another method involves comparing the FMR signature defined in the established region with at least one previously measured and stored FMR signature defined in the same region for the same pigment or blend of pigments. Regardless of the comparison method, the generated at least one FMR signature defined in the region is checked for compatibility or compared with at least one expected FMR signature. Such a comparison need not result in an exact match; it need only meet an accepted or minimum acceptable industry-defined threshold or confidence limit for classifying at least one machine-readable security feature as genuine or inauthentic. In other words, if the threshold is met, the security document or article is classified as authentic.

[0125]

[0125] Those skilled in the art may envision several modifications to the specific embodiments described above without departing from the spirit of the present invention, and such modifications are encompassed by the present invention. [Example]

[0126] The present invention will now be described in more detail with reference to non-limiting examples. The following Examples E1-E16 and Comparative Examples C1-C8 provide details regarding the preparation of the security inks described herein, and the magnetic and optical properties of the machine-readable security features obtained therefrom.

[0127] A. Magnetic Properties of Machine-Readable Security Features A-1. Ferromagnetic Resonance (FMR) Signature The ferromagnetic resonance of machine-readable security features derived from the inventive security inks E1-E16 and comparative inks C1-C8 was evaluated using a Phase FMR-40 instrument (Nanosc Instruments AB, Kista, Sweden) equipped with a 5403 magnet manufactured by GMW Associates (San Carlos, USA). The Phase FMR-40 was operated in CPW mode (coplanar waveguide), and a 5 mm x 5 mm sample of the security feature was placed upside down. To obtain the FMR spectrum of the measured sample, the RF frequency was fixed at 5 GHz, and the magnetic field was swept from 0 to 2500 Oe in steps of 10 Oe. A lock-in field modulation with a 20 Oe peak-to-peak amplitude and a frequency of 490 Hz was used, and the resulting FMR spectrum was displayed as the first derivative of the resonance signal.

[0128]

[0128] Two parameters were obtained from the FMR spectrum. Line center field (at 5 GHz): This is the field where the FMR spectrum of the security feature crosses zero (ie the field at the maximum amplitude of the resonance signal). Linewidth: This is the linewidth at half height or half prominence of the resonance signal.

[0129]

[0129] The line centre fields and line widths in Oe measured at an RF frequency of 5 GHz for the security features obtained from the inventive security inks E1 to E16 and the comparative inks C1 to C8 are reported in Table 7 below.

[0130]

[0130] At a given fixed RF frequency, the line center field and line width depend only on the molar concentration of element M in the YI(M)G pigment (i.e., the number of iron atoms substituted by element M in the crystal cell), regardless of the type of ink, as shown in Table 7.

[0131]

[0131] A-2. Integral magnetic susceptibility The integrated magnetic susceptibility of the machine-readable security features obtained from the inventive security inks E1-E16 and the comparative inks C1-C8 was evaluated using a QCD200 Mag instrument from Giesecke & Devrient GmbH (Munich, Germany). Homogeneous samples of dried and / or cured inventive security inks E1-E16 and comparative inks C1-C8 were measured according to Giesecke & Devrient guidelines (QCD 200 MAG Operating Manual Article 221312001).

[0132] The integrated magnetic susceptibility of the machine-readable security features obtained from the security inks E1 to E16 of the present invention and the comparative inks C1 to C8 are reported in Table 7 below.

[0133] B. Optical Properties of Machine-Readable Security Features B-1.L* value The L* values ​​of the machine-readable security features obtained from the inventive security inks E8-E16 and the comparative inks C4-C8 (screen printing inks) were independently obtained from measurements of the printed machine-readable security features according to CIELAB (1976), where a* and b* are color coordinates in Cartesian two-dimensional space (a* = color value along the red / green axis and b* = color value along the blue / yellow axis). The L*a*b* values ​​were independently measured using a Datacolor DC 45IR spectrophotometer (measurement geometry: 45 / 0°; spectrum analyzer: proprietary dual-channel holographic grating; 256-photodiode linear array used for both the reference and sample channels; light source: full-bandwidth LED illumination). The L* values ​​of the security features obtained from the inventive inks E8-E16 and the comparative inks C4-C8 are reported in Table 8 below.

[0134] B-2. IR Reflectance Spectrum The reflectance spectra of the machine-readable security features made from the inventive security inks E8-E16 and the comparative inks C4-C8 were measured independently using a Datacolor DC45IR from 400 nm to 1100 nm. 100% reflectance was measured using the instrument's internal standard. The reflectance values ​​(%) at selected wavelengths in the NIR range (700-1100 nm) of the security features obtained from the inventive security inks E8-E16 and the comparative inks C4-C8 are reported in Table 8 below.

[0135]

[0135] C.Y3Fe 5-x M x O 12 Pigment Pigments P1 and P2 to P7 were analyzed by laser diffraction measurement (Beckmann Laser LS) to determine their particle size d 50 The general formula of pigments P1 to P7 is Y3Fe 5-x Al x O 12 where the value of x varies from 0 to 1.5, corresponding to an Al / Fe ratio of 0 to 30 mol %. Stoichiometry and particle size d of pigments P1 to P7 50 are shown in Table 1 below.

[0136] [Table 1]

[0137] D. Preparation of security inks E1 to E15 of the present invention and comparative inks C1 to C8 D-1. Oxidative drying Intaglio inks E1-E6 and comparative inks C1-C2 To prepare the inventive security inks E1-E6 and comparative inks C1-C2, the ingredients listed in Table 2 were thoroughly mixed by hand with a spatula until visually homogeneous. The resulting paste inks were milled independently in two passes (first pass at 6 bar and second pass at 12 bar) in a three-roll mill (Buhler 200 SDV) at 25°C.

[0138] The viscosity of the thus obtained intaglio magnetic oxidative dried ink was measured using a Haake Roto Visco 1 rotational rheometer (40°C and 1000 s -1 , 20 mm cone plate, 0.5° geometry, 25 μm truncated tip).

[0139] [Table 2]

[0140] D-2. UV-curable Intaglio Ink E7 and Comparative Ink C3 To prepare the inventive security ink E7 and the comparative ink C3, the ingredients listed in Table 3 were mixed independently at room temperature for 3 minutes at 2500 rpm using a DAC 150 SP CM 31 speed mixer (Hauschild). The resulting pastes were milled independently in a three-roll mill (Buhler 200SDV) at 25°C in three passes (first pass at 8 bar pressure, second and third passes at 11 bar pressure).

[0141]

[0139] The viscosity of the ink was determined as described above in section D-1.

[0142] [Table 3]

[0143] D-3. UV-Cured Hybrid (Cationic / Radical) Screen Printing Inks E8-E14 and Comparative Inks C4-C6 To prepare the inventive security inks E8-E14 and comparative inks C4-C6, the components of the ink vehicle shown in Table 4 (i.e., all components of the ink except for the iridescent pigment and pigments P1-P7) were mixed and dispersed at 2000 rpm for 10 minutes at room temperature using a Dispermat (Model CV-3). Pigments P1-P7 were then added individually (except C4) and further dispersed at 2500 rpm for 3 minutes at room temperature. Finally, the iridescent pigment was added and dispersed at 2500 rpm for 3 minutes at room temperature.

[0144]

[0141] The viscosity values ​​shown in Table 4 were measured independently at 25°C using a Brookfield viscometer (Model "DV-I Prime", spindle S27 (100 rpm)).

[0145] [Table 4] JPEG2025530692000006.jpg225149

[0146] D-4. UV-curable radical screen printing ink E15 and comparative ink C7 To prepare the inventive security ink E15 and comparative ink C7, the components of the ink vehicle shown in Table 5 (i.e., all components of the ink except for the iridescent pigment and YIG pigment P6) were mixed and dispersed using a Dispermat (model CV-3) at 2000 rpm for 10 minutes at room temperature. Pigment P6 was then added (except for C7) and further dispersed at 2500 rpm for 3 minutes at room temperature. Finally, the iridescent pigment was added and dispersed at 2500 rpm for 3 minutes at room temperature.

[0147]

[0143] The viscosity of the ink was determined as described above in section D-3.

[0148] [Table 5]

[0149] D-5. Heat-drying solvent screen printing ink E16 and comparative ink C8 The components of the ink vehicle listed in Table 6 (i.e., all components of the ink except the iridescent pigment and YIG pigment) were mixed and dispersed at room temperature for 10 minutes at 2000 rpm using a Dispermat (Model CV-3). Pigment P6 was then added (except C8) and dispersed for 3 minutes at 2500 rpm, and finally the iridescent pigment was added and dispersed for 3 minutes at 2500 rpm to obtain the solvent screen printing security inks C8 and E15 listed in Table 6.

[0150]

[0145] The viscosity values ​​shown in Table 6 were measured independently at 25°C using a Brookfield viscometer (Model "DV-I Prime", spindle S27 (50 rpm)).

[0151] [Table 6]

[0152] E. Preparation of Machine-Readable Security Features Obtained from Security Inks E1-E16 of the Present Invention and Comparative Inks C1-C8 E-1. Machine-readable security features from oxidatively drying intaglio inks E1-E6 and comparison inks C1-C2 The oxidatively drying Intaglio inks E1-E6 and C1-C2 were printed independently on an Ormag intaglio proofing press using an intaglio plate consisting of a series of engravings of varying depth (approximately 20 μm to approximately 100 μm) and width (approximately 60 μm to approximately 500 μm) engraved in a "U" shape, such as to simulate the "guilloche" pattern on banknotes. The intaglio plate was heated to 60 °C, and the oxidatively drying Intaglio inks E1-E6 and C1-C2 were applied to credit paper (BNP paper from Louisenthal, 100 g / m²) using a polymer hand inking roller. 2 The ink was applied independently to a 20 cm x 4 cm (approx. 20 cm x 4 cm) and excess ink was manually wiped off with paper. The size of the guilloche pattern was 5.4 cm x 2.5 cm.

[0153] The resulting security features were allowed to dry in the dark for 7 days. Three samples of each security ink were printed and subjected to the tests described above in sections A-1 and A-2.

[0154] E-2. Machine-readable security features from UV-cured intaglio ink E7 and comparison ink C3 The UV-cured Intaglio inks E7 and C3 were printed independently as described in section E-1. A Technigraf AKTIPRINT 18-2 mercury UV dryer (approximately 200 mJ / cm) was used. 2 The printed security features were cured using a 1000 Watts UV curing machine (with a belt speed of 10 m / min corresponding to a dose of 100 Watts UV). Three samples of each security ink were printed and subjected to the tests described above in sections A-1 and A-2.

[0155] E-3. Machine-Readable Security Features from UV-Cured Hybrid (Cationic / Radical) and Radical Screen Printing Inks E8-E15 and Comparative Inks C4-C7 UV-curable screen printing inks E8 to E15 and C4 to C7 were printed on a sheet of credit paper (BNP paper from Louisenthal, 100 g / m) using a 90 thread / cm screen (230 mesh) to form a machine-readable security feature in the form of a cured coating layer with a thickness of approximately 20 μm. 2 The printed patterns had a size of 3.5 cm x 3.5 cm.

[0156] After the printing step, each security feature was printed using a 200W / cm immersion lamp from IST Metz GmbH (two lamps: iron-doped mercury lamp 200W / cm 2 + mercury lamp 200W / cm 2 The features were cured by exposing them twice to UV-Vis light at a speed of 100 m / min under a curing unit manufactured by ), Three samples of each security ink were printed and subjected to the tests described above in sections A-1 to B-2.

[0157] E-4. Machine-Readable Security Features from Heat-Drying Solvent Screen Printing Ink E16 and Comparison Ink C8 Heat-drying solvent screen printing inks E16 and C8 are printed on a sheet of credit paper (BNP paper manufactured by Louisenthal, 100 g / m) using a 90 thread / cm screen (230 mesh) to form a machine-readable security feature in the form of a dried coating layer with a thickness of approximately 6-9 μm. 2 The printed patterns had a size of 3.5 cm x 3.5 cm.

[0158]

[0152] After the printing step, each security feature was dried for about 1 minute in a hot air dryer at a temperature of about 50° C. Three samples of each security ink were printed and subjected to the tests described above in sections A-1 to B-2.

[0159] F. Machine-Readable Security Feature Results from Security Inks E1-E16 of the Invention and Comparative Inks C1-C8 F-1. FMR signature (line width and line center field) and integrated magnetic susceptibility Table 7 shows the FMR signature characteristics (line width and line center field) and integrated magnetic susceptibility of machine-readable security features obtained by printing and drying and / or curing the inventive security inks E1 to E16 and comparative inks C1 to C8. Testing was carried out according to the procedures described in sections A-1 and A-2.

[0160] [Table 7]

[0161] F-2. Optical properties (L*a*b* values ​​and NIR reflectance) Table 8 shows the optical properties of machine-readable security features obtained by printing and drying / curing screen-printed security inks E8-E16 of the present invention and comparative inks C4-C8. Testing was carried out according to the procedures described in sections B-1 and B-2.

[0162]

Table 8

Claims

1. At least one non-luminescent, undoped Y ３ Fe ５－ｘ M ｘ O １２ A security ink composition containing a pigment, x satisfies the condition 0 ≤ x ≤ 1.25, M is selected from the group consisting of aluminum, gallium, or calcium and mixtures thereof, and at least one coated, preferably printed, machine-readable security feature derived from the security ink composition has a surface area of ​​at least about 200 × 10 after drying and / or curing. －１２ I understand ３ It has an integrated magnetic susceptibility and exhibits a ferromagnetic resonance (FMR) signature for authentication purposes. Security ink composition.

2. The security ink composition according to claim 1, wherein x satisfies the condition 0.10 ≤ x ≤ 1.

25.

3. The security ink composition according to claim 1 or 2, wherein x satisfies the condition 0.25 ≤ x ≤ 1.

00.

4. The security ink composition according to claim 1 or 2, wherein M is aluminum.

5. The security ink composition according to claim 1 or 2, wherein the pigment is present in a maximum of 40% by weight, preferably a maximum of 20% by weight, of the security ink composition.

6. x satisfies the conditions 0 ≤ x ≤ 5, preferably 0 ≤ x ≤ 4.

99. M is selected from the group consisting of aluminum, gallium, calcium, or mixtures thereof. At least one coated, preferably printed, machine-readable security feature derived from the security ink composition exhibits a ferromagnetic resonance (FMR) signature for authentication purposes after drying and / or curing. At least one additional non-luminescent non-doped Y ３ Fe ５－ｘ M ｘ O １２ The security ink composition according to claim 1 or 2, comprising a series pigment.

7. The security ink composition according to claim 1 or 2, further comprising at least one machine-readable compound selected from the group consisting of luminescent pigments, IR-absorbing pigments, or SERS compounds.

8. The security ink composition according to claim 1 or 2, wherein the security ink composition is an intaglio ink composition having a viscosity in the range of about 3 to 60 Pa·s at 40°C.

9. The security ink composition according to claim 1 or 2, wherein the security ink composition is a screen printing ink composition having a viscosity in the range of about 0.05 to 5 Pa·s at 25°C.

10. A machine-readable security feature comprising at least one security ink composition according to claim 1 or 2.

11. A security document or article comprising at least one machine-readable security feature as described in claim 10.

12. A security document or article according to claim 11, comprising at least one additional different security feature.

13. A method for authenticating security documents or articles, a) the step of providing the security document or article described in claim 11, b) Defining at least one area of ​​the security document or article containing the at least one machine-readable security feature for the purpose of detecting an FMR signal; c) The steps of detecting and recording the FMR spectrum of the at least one machine-readable security feature and providing a recorded FMR spectrum containing enough data points to establish at least one FMR signature, d) Parameterizing the recorded FMR spectrum or using it directly to establish an FMR signature defined in at least one region; e) a step of comparing the FMR signature defined in the at least one region established from step d) with at least one predefined or expected FMR signature, f) A step of determining the authenticity of the security document or article based on the comparison operation performed under step e), A method that includes this.

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