Security pigment and optical security element

Abstract

The invention relates to a security pigment and an optical security element. The invention discloses an article. The article comprises a substrate; and a composition on the substrate, the composition comprising a liquid medium and a translucent magnetic pigment, the translucent magnetic pigment comprising a translucent metal magnetic material and a dielectric material for use as a light interference cavity. A method of manufacturing an article is also disclosed.

Description

[0001] This application is a divisional application of the application with the application date of October 8, 2020, application number 202080077728.8, and invention name “Security Pigments and Optical Security Elements”. Related applications

[0002] This application claims the benefit of priority to U.S. Provisional Patent Application No. 62 / 912,518, filed on October 8, 2019, the entire disclosure of which is hereby incorporated by reference herein. Field of the Invention

[0003] The present disclosure generally relates to an article comprising a substrate; and a composition on the substrate, the composition comprising a liquid medium and a translucent magnetic pigment, the translucent magnetic pigment comprising a translucent metallic magnetic material and a dielectric material that functions as an optical interference cavity. The translucent magnetic pigment is disclosed, as are methods of making the article and the translucent magnetic pigment. Background of the Invention

[0004] Pigments containing iron oxides, such as fully dielectric pigments, exhibit different colors in reflection at normal viewing angles, but are limited to yellow-red to brown colors in transmission. For many applications, this is not a big deal, but for security devices printed on top of transparent windows in banknotes, the lack of a full range of colors limits the product's value. SUMMARY OF THE INVENTION

[0005] In one aspect, an article is disclosed, comprising a substrate; and a composition on the substrate, the composition comprising a liquid medium and a translucent magnetic pigment, the translucent magnetic pigment comprising a translucent metallic magnetic material and a dielectric material serving as an optical interference cavity.

[0006] In another aspect, a method of making an article is disclosed, the method comprising providing a substrate; and depositing a first composition on a first surface of the substrate, wherein the first composition comprises a liquid medium and a translucent magnetic pigment.

[0007] This application provides the following: 1) An article comprising: substrate; and A composition on the substrate comprises a liquid medium and a translucent magnetic pigment, wherein the translucent magnetic pigment comprises a translucent metallic magnetic material and a dielectric material serving as an optical interference cavity.

[0008] 2). The article according to 1), wherein the substrate is a polymer substrate or a paper substrate having a transparent window.

[0009] 3). The article according to 1), wherein the composition is a first composition on a first side of the substrate; and further comprising a second composition on a second side of the substrate opposite to the first side.

[0010] 4). The article according to 3), wherein the first composition comprises a first translucent magnetic pigment, the second composition comprises a second translucent magnetic pigment, and the first translucent magnetic pigment and the second translucent magnetic pigment are different.

[0011] 5) The article according to 1), wherein the dielectric material of the translucent magnetic pigment can be present in multiple layers.

[0012] 6). The article according to 5), wherein a plurality of dielectric material layers are alternated with metal material layers.

[0013] 7). The article according to 1), wherein the translucent magnetic pigment exhibits a first color in reflection and a second color in transmission.

[0014] 8). The article according to 4), wherein the first translucent magnetic pigment exhibits a first color in reflection and a second color in transmission, and the second translucent magnetic pigment exhibits a third color in reflection and a fourth color in transmission.

[0015] 9). The article according to 1), wherein the article further comprises a third composition comprising a liquid medium and a magnetizable color-changing opaque pigment.

[0016] 10). The article according to 9), wherein the third composition is present on at least one of the substrate and the first composition.

[0017] 11). The article according to 10), wherein the substrate comprises a transparent window, and the first composition is on the transparent window, and the third composition is on the first composition.

[0018] 12). The article according to 10), wherein the substrate comprises a transparent window, and the third composition is on the transparent window, and the first composition is on the third composition.

[0019] 13) A method of manufacturing an article, comprising: providing a substrate; and A first composition is deposited on a first surface of a substrate, wherein the first composition includes a liquid medium and a translucent magnetic pigment.

[0020] 14). The method according to 13), further comprising depositing a second composition on a second surface of the substrate opposite to the first surface.

[0021] The additional features and advantages of various embodiments will be set forth in part in the following description and will be in part apparent from the description or may be learned by practicing various embodiments. The purposes and other advantages of various embodiments will be realized and obtained by means of the elements and combinations particularly pointed out in the description herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Features of the present disclosure are illustrated by way of example and not limitation in the following figures, in which like numerals represent like elements, and in which: Figure 1 is a cross-section of a translucent magnetic pigment particle according to aspects of the present invention; Figure 2 yes Figure 1 Spectra of reflection and transmission of translucent magnetic pigment particles; Figure 3 yes Figure 1 Spectra of reflection and transmission of translucent magnetic pigment particles; Figure 4 is a cross-section of a translucent magnetic pigment particle according to another aspect of the present invention; Figure 5 yes Figure 4 Spectra of reflection and transmission of translucent magnetic pigment particles; Figure 6 is a schematic diagram illustrating reflected light from an article after the pigment is aligned in a magnetic field; Figure 7A is a schematic diagram illustrating the optical effect of a "rolling bar" on an object; Figure 7B is a schematic diagram illustrating a "rolling bar" optical effect on an article according to aspects of the present invention (left) and an article using conventional opaque magnetic pigments (right); Figure 8 is a schematic diagram illustrating reflected light from an article and a "rolling bar" optical effect with a dark background to show contrast according to aspects of the present invention; Figure 9 is a schematic diagram illustrating reflected light from an article and a "rolling bar" optical effect with a bright background to show contrast according to aspects of the present invention; Figure 10 is a schematic diagram illustrating transmitted light from an article and a "rolling bar" optical effect according to aspects of the present invention; Figure 11is a cross-section of an article comprising a first composition on a first side of a substrate and a second composition on a second side of the substrate; Figure 12 is a diagram illustrating an aspect of the present invention from Figure 11 Schematic diagram of reflected light from an object in the image; Figure 13 is a diagram illustrating another aspect of the present invention from Figure 11 Schematic diagram of the transmitted light of an object in; Figure 14 is a schematic diagram illustrating an article comprising a first composition and a third composition; Figure 15 The diagram shows the Figure 14 Schematic diagram of reflected light from an article in FIG; and Figure 16 The diagram shows the Figure 14 Schematic diagram of the transmitted light of an object in . Detailed Description of the Invention

[0023] For simplicity and illustrative purposes, the present disclosure is described by reference to the examples of the present disclosure. In the following description, many specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be readily apparent that the present disclosure can be implemented without being limited to these specific details. In other cases, some methods and structures are not described in detail in order to avoid unnecessarily obscuring the present disclosure.

[0024] Furthermore, the elements depicted in the accompanying drawings may include additional components, and some components depicted in those drawings may be removed and / or modified without departing from the scope of the present disclosure. Furthermore, the elements depicted in the drawings may not be drawn to scale, and therefore, these elements may have sizes and / or configurations that are different from those shown in the drawings.

[0025] It should be understood that both the foregoing general description and the following detailed description are merely exemplary and explanatory and are intended to provide an explanation of the various embodiments of the present teachings. In its broad and varied embodiments, disclosed herein are pigments, compositions comprising the pigments, articles comprising the compositions; and methods of making and using the pigments, compositions, and articles.

[0026] This disclosure describes a translucent magnetic pigment 12. The translucent magnetic pigment 12 can exhibit multiple reflected colors and multiple transmitted colors. The translucent magnetic pigment 12 can be a magnetic dichroic pigment. At a normal angle, the translucent magnetic pigment 12 can reflect a first color and transmit a second color, different from the first color. When the angle changes from the normal angle, such as a change in viewing angle, the translucent magnetic pigment 12 can reflect a third color and transmit a fourth color. For ease of reference herein, the terms "first color," "second color," "third color," and "fourth color" are used to distinguish between different colors and should not be used to limit the term to a specific color.

[0027] The translucent magnetic pigment may include a translucent metallic magnetic material 1 and dielectric materials 2, 3 that function as light interference cavities. In one embodiment, the translucent magnetic pigment 12 may have the following structure: dielectric (2, 3) / semi-transparent metallic magnetic material (1) / dielectric (2, 3), wherein the dielectric may include one or more layers of dielectric materials 2, 3. For example, the translucent magnetic pigment 12 may include multiple layers of dielectric materials 2, 3 on opposite sides of a central translucent metallic magnetic material 1. The multiple layers of dielectric materials 2, 3 may include alternating layers of two different dielectric materials, such as a first dielectric material 2 and a second dielectric material 3. The multiple layers of dielectric materials 2, 3 may function as light interference cavities, which result in color changes at angles.

[0028] In the aspect, the translucent magnetic pigment 12 may include a translucent metallic magnetic material 1, dielectric materials 2, 3, and may further include a metal material 4. The translucent magnetic pigment 12 may have the following structure: (metal material / dielectric material) n / Translucent Metallic Magnetic Materials / (Dielectric Materials / Metal Materials) n , where n is an integer greater than or equal to 1.

[0029] The translucent magnetic pigment 12 may include one or more layers of a translucent metallic magnetic material 1, one or more layers of a dielectric material 2, 3, and optionally one or more layers of a metallic material 4. The translucent magnetic pigment 12 may include an even number of layers, such as two, four, six, etc. The translucent magnetic pigment 12 may include an odd number of layers, such as three, five, seven, etc.

[0030] The dielectric materials 2 and 3 used in the disclosed translucent magnetic pigments 12 can be any low refractive index material 3, any high refractive index material 2, and combinations thereof. For example, multiple layers of MgF2, SiO2, Ta2O5, TiO2, ZnS, and other materials with both low and high refractive indices can be formed. The dielectric materials 2 and 3 can be present in layers or as particles within a layer. In certain aspects, the dielectric materials 2 and 3 present in one or more layers of the translucent magnetic pigment 12 can be the same or different.

[0031] The dielectric material may be a high refractive index material 2, ie having a refractive index greater than about 1.65. The high refractive index material 2 may include oxides, sulfides, carbides, niobates and nitrides. Non-limiting examples of the high refractive index material 2 include zinc sulfide (ZnS), zinc oxide (ZnO), zirconium oxide (ZrO2), titanium dioxide (TiO2), magnesium aluminate (MgAl2O4), titanium nitride (TiN), diamond-like carbon, indium oxide (In2O3), indium tin oxide (ITO), tantalum pentoxide (Ta2O5), cerium oxide (CeO2), yttrium oxide (Y2O3), europium oxide (Eu2O3), iron oxides such as (II) iron (III) oxide (Fe3O4) and iron oxide (Fe2O3), hafnium nitride (HfN), hafnium carbide (HfC), hafnium oxide (HfO2), lanthanum oxide (La2O3), magnesium oxide (MgO), neodymium oxide (Nd2O3), praseodymium oxide (Pr6O3), and tantalum oxide (TdO3). 11 ), samarium oxide (Sm2O3), antimony trioxide (Sb2O3), silicon, silicon monoxide (SiO), selenium trioxide (Se2O3), tin oxide (SnO2), tungsten trioxide (WO3), or a combination thereof.

[0032] The dielectric material may be a low refractive index material 3, i.e., having a refractive index of less than about 1.65. The low refractive index material 3 may include fluorides, oxides, and chalcogenides. Non-limiting examples of the low refractive index material 3 include silicon dioxide (SiO2), aluminum oxide (Al2O3), metal fluorides such as magnesium fluoride (MgF2), aluminum fluoride (AlF3), cerium fluoride (CeF3), lanthanum fluoride (LaF3), sodium aluminum fluoride (e.g., Na3AIF6 or Na5Al3f3), and the like. 14 ), neodymium fluoride (NdF3), samarium fluoride (SmF3), barium fluoride (BaF2), calcium fluoride (CaF2), lithium fluoride (LiF), or a combination thereof. Organic monomers and polymers can be used as the low refractive index material 3, including dienes or olefins, such as acrylates (e.g., methacrylates), perfluoroolefins, polytetrafluoroethylene (Teflon), fluorinated ethylene propylene (FEP), or a combination thereof.

[0033] The dielectric materials 2, 3 can be deposited as a dielectric stack having a predetermined number of layers. In this example, the stack can include one or more layers of a low refractive index material 3 and one or more layers of a high refractive index material 2. The layers of low refractive index material (low refractive index layers) 3 and the layers of high refractive index material (high refractive index layers) 2 can alternate. The alternating layers of high refractive index layers and low refractive index layers can be repeated as many times as desired. The alternating layers can be stacked in any order, for example, the layers can be arranged in a (H / L) order. n 、(H / L) nH, or L (H / L) n , where H represents the higher refractive index layer 2 and L represents the lower refractive index layer 3, and n is an integer greater than or equal to 1. Any number of different materials with different optical and / or physical thicknesses can be used to deposit any number of layers. In practice, the number of layers is limited by the total thickness that can be produced as a pigment, which is in the range of up to 10 microns. In this way, by controlling the layer thickness and refractive index of each dielectric layer, customized optical designs are possible. In this aspect, the dielectric layer can be a transparent layer or a colored layer.

[0034] The translucent magnetic material 1 used in the disclosed translucent magnetic pigment 12 can provide a function selected from optical functions, magnetic functions, and combinations thereof. In the optical function, the translucent metallic magnetic material 1 can serve as a translucent reflector and absorber in a Fabry-Perot structure. In the magnetic function, the translucent metallic magnetic material 1 can be carefully selected to provide alignment of the translucent magnetic pigment 12 when dispersed in a layer of the composition. A magnetic field 16 can be applied to the composition 14 before the material is cured into a solid for forming a predetermined optical effect.

[0035] The translucent metallic magnetic material 1 can be present in the translucent magnetic pigment 12 as a thin layer or as particles in a layer (including as multiple layers within the translucent magnetic pigment 12). In some aspects, the translucent metallic magnetic material 1 present in the translucent magnetic pigment 12 can be a single material or a plurality of different materials. The translucent metallic magnetic material 1 can be located in the center of the translucent magnetic pigment 12.

[0036] The translucent metallic magnetic material 1 may include a magnetically permeable material, a magnetically orientable material, and combinations thereof. The translucent metallic magnetic material 1 may be a material selected from ferromagnetic materials and ferrimagnetic materials, such as materials having soft magnetic properties or hard magnetic properties. The translucent metallic magnetic material 1 may be a ferromagnetic material positioned in the central layer of the translucent magnetic pigment 12.

[0037] Non-limiting examples of translucent metallic magnetic materials 1 include iron, nickel, cobalt, alloys thereof with other ferromagnetic metals and non-ferromagnetic metals, and metalloids. Other examples of translucent metallic magnetic materials 1 include, but are not limited to, gadolinium, terbium, dysprosium, erbium, and blends, alloys, or oxides thereof. Non-limiting examples of blends or alloys include Fe / Si, Fe / Ni, Fe / Co, Fe / Cr / Al, Fe / terbium, Fe / Ni / Mo, Fe / Cr, Ni / Cr, Ni / Co, Co / Pt, Co / Cr, and combinations thereof. In aspect, the translucent metallic magnetic material 1 may be a composition 14 comprising a polymer containing iron oxide particles. SmCo5, NdCo5, Sm2CO5, or the like may also be used.17 、Nd2Fe 14 B, Sr6Fe2O3, TbFe2, NiAl, NiAl3, Ni3Al, Al-Ni-Co type hard magnets and combinations thereof, as well as Fe3O4, NiFe2O4, MnFe2O4, CoFeO4 type spinel ferrites, or YIG or GdIG type garnets and combinations thereof. In the aspect, the translucent metallic magnetic material 1 can be ferritic stainless steel.

[0038] The translucent metallic magnetic material 1 can be selected for its reflective or absorptive properties as well as its magnetic properties. The translucent metallic magnetic material 1 can be formed from a material having magnetic particles and non-magnetic particles in a non-magnetic medium, or a material having magnetic particles (or flakes). The translucent metallic magnetic material 1 can be a different layer, or can be used as a reflector layer (magnetic reflector layer) or an absorber layer.

[0039] Although this wide range of translucent metallic magnetic materials 1 can be used, "soft" magnets can be used in aspects. The translucent metallic magnetic material 1 can be easily magnetized and demagnetized by soft magnetic properties. As used herein, the term "soft magnet" refers to any material that exhibits ferromagnetic properties but has a substantially zero remanence after being exposed to a magnetic force. A soft magnet can show a rapid response to an applied magnetic field 16, but has very low magnetic characteristics (coercive field (Hc) = 0.05 Oersted-300 Oersted (Oe)) or zero magnetic characteristics, or maintains very low magnetic lines of force after the magnetic field 16 is removed. Similarly, as used herein, the term "hard magnet" (also referred to as a permanent magnet) refers to any material that exhibits ferromagnetic properties and has a persistent remanence after being exposed to a magnetizing force. A ferromagnetic material is any material that has a magnetic permeability that is substantially greater than 1 and exhibits hysteresis properties. In the aspect, any translucent metallic magnetic material 1 can be used as long as the material is capable of orienting the translucent magnetic pigment 12 in the magnetic field 16 .

[0040] The translucent magnetic pigment 12 may also include a metallic material 4. The metallic material 4 may be a translucent absorber. The metallic material 4 may be the same as or different from the translucent metallic magnetic material 1 discussed herein. The metallic material 4 may include a metal and / or a metal alloy. In one aspect, the metallic material 4 may include a material having reflective properties. An example of a reflective material may be aluminum, which has good reflectivity properties, is inexpensive, and is easy to form or deposit as a thin layer. However, other reflective materials may also be used instead of aluminum. Non-limiting examples of the metallic material 4 may include aluminum, copper, silver, gold, platinum, palladium, nickel, cobalt, niobium, chromium, tin, combinations thereof, and alloys of these or other metals. In one aspect, the metallic material 4 may be a white metal or a light-colored metal. Other useful metallic materials 4 include, but are not limited to, transition metals and lanthanide metals and combinations thereof.

[0041] A method for making a translucent magnetic pigment 12 can include depositing a first dielectric material 3, optionally including a lift-off layer, on a substrate; depositing a translucent metallic magnetic material 1 on the first dielectric material 3; and depositing a second dielectric material 3 on the translucent magnetic material 1. The method can also include depositing additional dielectric materials 2 on the first dielectric material and / or the second dielectric material 3, for example, to form a dielectric stack of alternating layers of high-refractive-index dielectric material 2 and low-refractive-index dielectric material 3. The method can also include depositing the first dielectric material 3 on a first metallic material 4; and / or depositing the second metallic material 4 on the second dielectric material 3. After deposition is complete, the material can be removed from the substrate and sized to a size suitable for the optically variable pigment. The thickness of the pigment is determined by the cumulative layer thickness, which determines other dimensions, and these can range from 5 microns to 50 microns D50.

[0042] The translucent magnetic pigment 12 can be dispersed in a liquid medium to form a composition 14. The composition 14 can be an ink, a coating, or a paint. The liquid medium can be a transparent, colorless organic binder. Non-limiting examples of the liquid medium can include solvents, for example, acetates such as ethyl acetate, propyl acetate, and butyl acetate; acetone; water; ketones such as dimethyl ketone (DMK), methyl ethyl ketone (MEK), sec-butyl methyl ketone (SBMK), tert-butyl methyl ketone (TBMK), cyclopentanone, and anisole; glycols and glycol derivatives such as propylene glycol methyl ether and propylene glycol methyl ether acetate; alcohols such as isopropyl alcohol and diacetone alcohol; esters such as malonic esters; heterocyclic solvents such as n-methylpyrrolidone; hydrocarbons such as toluene and xylene; coalescing solvents such as glycol ethers; and mixtures thereof. The liquid medium can also be a radiation-curable ink or paint having a high solids content and a low solvent content, or a hybrid system that is radiation-curable and does contain a solvent. In aspects, the liquid medium can be present in an amount ranging from about 0% to about 99.9% by weight, such as from about 0.005% to about 99% by weight, and as a further example, from about 0.05% to about 90% by weight, relative to the total weight of the composition. In aspects, the composition 14 can include any pigment including a translucent metallic magnetic material 1 and capable of aligning in a magnetic field 16.

[0043] The composition 14 can be placed in a magnetic field 16 to align the translucent magnetic pigments 12 in the liquid medium. Once the translucent magnetic pigments 12 are aligned, the composition 14 can be cured to fix the aligned translucent magnetic pigments 12.

[0044] The composition 14 can be printed on a substrate 18 to form an article 22. In one aspect, the article 22 can be a banknote having a transparent window 38. The article 22 can include a substrate 18 having a coating of the composition 14 including a liquid medium and the disclosed translucent magnetic pigment 12.

[0045] Example Example 1 - A semi-transparent magnetic pigment 12 was formed having the following structure (9 layers): (4) Al - 4 nm / (3)MgF2 - 163 nm / (4) Al - 3 nm / (3) MgF2 - 163 nm / (1) Co - 2 nm / (3) MgF2 -163 nm / (4) Al - 3 nm / (3) MgF2 - 163 nm / (4) Al - 4 nm.

[0046] At normal viewing angles, the color of the translucent magnetic pigment 12 is blue (a first color) in reflection and yellow (a second color) in transmission. An article 22 printed with a composition 14 including the translucent magnetic pigment 12 changes its reflected color from blue to purple. In transmission, the color of the article 22 changes from yellow to green. Figure 5 The figure shows that Figure 2 A spectrum of a composition 14 including a translucent magnetic pigment 12 is shown in an article 22 , where the composition 14 is printed on top of a substrate 18 .

[0047] An emblem printed with translucent magnetic pigment 12 on top of the transparent window 38 of the banknote may appear blue (a first colour) in reflection and yellow (a second colour) in transmission.

[0048] Example 2 - As Figure 1 As shown, a translucent magnetic pigment 12 having the following structure is formed: (2) ZnS - 100 nm / (3) MgF2 - 310 nm / (2) ZnS - 138 nm / (1) Ni - 14 nm / (2) ZnS - 138 nm / (3) MgF2 - 310 nm / (2)ZnS - 100 nm.

[0049] like Figure 2 As shown, at a normal viewing angle, the color of the translucent magnetic pigment 12 is green (first color) in reflection and purple (second color) at an oblique angle. In transmission, the translucent magnetic pigment 12 is purple (third color) at a normal viewing angle and green (fourth color) at an oblique angle.

[0050] Example 3 - As Figure 1 As shown, a translucent magnetic pigment 12 having the following structure is formed: (2) ZnS - 130 nm / (3) MgF2 - 316 nm / (2) ZnS - 160 nm / (1) Co - 6 nm / (2) ZnS - 160 nm / (3) MgF2 - 316 nm / (2) ZnS - 130 nm.

[0051] like Figure 3 As shown, at a normal viewing angle, the color of the translucent magnetic pigment 12 is orange (a first color) in reflection and blue (a second color) in transmission. In reflection, as the angle changes from the normal angle, the orange gradually changes to green (a third color). In transmission, as the angle changes from the normal angle, the color changes from blue to purple (a fourth color).

[0052] The cobalt layer (or another transparent metallic magnetic material 1) can respond to an applied magnetic field 16 and can align the translucent magnetic pigment 12 along the lines of the magnetic field 16. The alignment of the translucent magnetic pigment 12 in the composition 14, which also includes a liquid medium, can result in an optically convex or concave reflector similar to a Fresnel mirror. Incident light reflected from the translucent magnetic pigment 12 can cause a shift in the focus of the reflected light in response to tilting the article 22 printed with the composition 14. This shift in the focus of the reflected light can create a three-dimensional perception for the observer. There can also be a gradual change from a first color of the reflected light to a second color of the reflected light. When the article 22 printed with the composition 14 is viewed in transmission, the transmitted color is an unappealing gray, and the three-dimensional optical effect is not visible.

[0053] like Figure 6 As shown, light 26 from light source 20 can impinge on translucent magnetic pigment 12 and can be reflected in direction 24 toward observer 28. Translucent magnetic pigment 12, with its plane oriented along the curve of magnetic field 16, can create a convex mirror that observer 28 perceives as a bright band of reflected light that moves within article 22 upon tilting or rotation of substrate 18. This effect is known as the "rolling bar optical effect."

[0054] The disclosed translucent magnetic pigment 12 has a higher transparency than inks including conventional color-changing pigments. Figure 7A and Figure 7B As shown, an image 30, such as a star, is printed on a substrate 18 using a composition 14, such as an ink, that includes 25% by weight of the translucent magnetic pigment 12 of Example 3. This image is printed on top of a second image 32, such as a rose, that was previously printed on the substrate 18. Figure 6 An article 22 with a wet composition 14 is placed in a magnetic field 16 generated by a permanent magnet. Translucent magnetic pigments 12 are aligned to produce a "rolling bar" optical effect. UV light is used to cure the composition 14, so that the translucent magnetic pigments 12 are fixed in the liquid medium of the composition 14 at an angle different from the surface of the substrate 18 defined by the angle of the field. Substrate 18 is tilted, with its upper edge pointing away from the camera in a direction 34. In this case, the bright band 36 of the "rolling bar" optical effect moves to the lower side of image 30. Second image 32 remains highly visible. Article 22 made with conventional magnetizable color-shifting pigments renders the second image completely opaque. Figure 7A The figure shows two images. The left image shows an article made with translucent magnetic pigment 12 at a normal viewing angle, where the second image is highly visible. The right image shows an article made with conventional magnetizable pigment.

[0055] Example 4- Figures 8-10 The "rolling bar" optical effect produced by the composition 14 comprising the translucent magnetic pigment 12 described in Example 3 is demonstrated. The composition 14 in the shape of the number 20 is printed on a transparent window 38 of a substrate 18, such as a polymeric substrate. Figure 8 In the figure, light source 20 and observer 28 are in front of object 22. Light ray 26 strikes object 22 and is reflected along direction 24 toward observer 28. At normal viewing angle, the number "20" appears bronze with a bright gold band in the center. A black card 40 is placed behind object 22 to highlight the high contrast of the bright gold band. Figure 8 The figure shows that at a first angle, the translucent magnetic pigment 12 may reflect a first color, such as a bright gold.

[0056] When the white card 40 is placed behind the object 22, the contrast of the object 22 becomes less noticeable, e.g. Figure 9 The "scroll bar" is still highly visible as a bright gold band.

[0057] When the light source 20 is located behind the object 22, the appearance of the object 22 changes, such as Figure 10 Specifically, light is directed toward the viewer 28 via light rays 26 and 24 passing through the transparent window 38 of the substrate 18. The composition 14 containing the translucent magnetic pigment 12 is printed on the transparent window 38. Except for the transparent window 38 of the substrate 18, the liquid medium of the composition 14 is clear and transparent. Figure 10 As shown, the "rolling bar" is blue in transmission, and this causes the image "20" to be blue when viewed through the transparent window 38. Reflected light ( Figure 8 and Figure 9 ) and transmitted light ( Figure 10 ) is unique to the translucent magnetic pigment 12, the composition 14 including the translucent magnetic pigment 12, and the article 22 having the composition 14. Figure 10 The figure shows that at a first angle, the translucent magnetic pigment 12 can transmit a second color (blue) that is different from the reflected first color ( Figure 8 bright gold in the ).

[0058] Example 5- Figure 11-13 The figure shows an article 22 having a first composition 14A on a first side of a substrate 18 and a second composition 14B on a second side of the substrate 18. Both have the same rectangular shape, 14B being parallel to the length of the substrate and 14A being perpendicular to the length of the substrate. The substrate 18 is a Figures 8-101 and 1 . A polymer banknote having a transparent window 38 similar to the transparent window shown. A first composition 14A includes a first translucent magnetic pigment 12A that appears orange (a first color) when reflected and blue (a second color) when transmitted. A second composition 14B includes a second translucent magnetic pigment 12B that appears blue (a third color) when reflected and yellow (a fourth color) when transmitted. The first composition 14A and the second composition 14B are subjected to a magnetic field 16 to align the respective translucent magnetic pigments 12A, 12B to produce a "rolling bar" effect. The rolling bar effect moves in the length direction of each rectangular printed shape. The "rolling bar" effect is exemplary, and any other optical effect may be used.

[0059] like Figure 12 As shown, article 22 reflects incident light 24 toward viewer 28. Article 22 appears as a horizontal orange / gold rectangular region from first composition 14A and two blue squares from second composition 14B, as the gold region overlaps the blue region in the middle square and obscures the center portion of region 14B. When article 22 is tilted from side to side, a "rolling bar" effect can be seen in the gold region from first composition 14A. When article 22 is tilted from front to back, a "rolling bar" effect can be seen in the blue region from second composition 14B. The plane of the magnetically aligned translucent magnetic pigment 12 is aligned with the viewing direction, so the translucent magnetic pigment 12 does not obstruct the view. The rolling bars on the backside second composition 14B show through the frontside first composition 14A.

[0060] When the light source 20 is placed behind the substrate 18, the appearance of the article 22 is completely different, e.g. Figure 13 As shown in FIG. 2 , light 26 strikes the back side of substrate 18 and passes through transparent window 38 and first composition 14A and second composition 14B containing translucent magnetic pigment 12. First composition 14A appears cyan in transmission, and second composition 14B appears yellow in transmission. The overlapping region 42 of first composition 14A and second composition 14B appears green due to the mixing of the transmitted cyan (14A) and yellow (14B) light.

[0061] Example 6 - Article 22 can include substrate 18 and composition 14 on substrate 18. Composition 14C can include a liquid medium and translucent magnetic pigment 12, and can also include a magnetizable color-shifting opaque pigment 44. In another aspect, article 22 can include substrate 18 and a first composition 14 on substrate 18; and a third composition 46 on at least one of substrate 18 and first composition 14, the third composition 46 including a liquid medium and a magnetizable color-shifting opaque pigment 44. Article 22 can produce a color-matching optical effect at specific viewing and lighting angles. The translucent magnetic pigment 12 and the magnetizable color-shifting opaque pigment 44 can change color from a first color to a second color, for example, from gold to green, when article 22 is tilted away from viewer 28. However, the second color of the translucent magnetic pigment 12 can have a lower chroma than the second color of the magnetizable color-shifting opaque pigment 44. This difference in chroma can be a result of the lower reflectivity and higher transmittance of the translucent magnetic pigment 12 compared to the magnetizable color-shifting opaque pigment 44. In particular, the translucent magnetic pigment 12 can have a lower reflectivity because the translucent metallic magnetic material 1 used as a reflector is translucent. The translucent metallic magnetic material 1 reflects less light than an opaque reflector, such as aluminum. For this reason, conventional magnetic pigments exhibit a higher reflectivity than the translucent magnetic pigment 12. On the other hand, the translucent metallic magnetic material 1 in the translucent metallic magnetic pigment 12 provides a higher light transmittance. The translucent metallic magnetic material 1 does not block light as it passes through the translucent magnetic pigment 12, as is the case with conventional opaque pigments. For conventional opaque pigments, this difference can be reduced by using lower pigment coverage, lower ink loading, and / or a thinner ink layer compared to the translucent magnetic pigment 12.

[0062] like Figure 14As shown, the article 22 includes a substrate 18 having a transparent window 38. A first composition 14A comprising a liquid medium and a translucent magnetic pigment 12 is printed in the form of a circle on the transparent window 38 and aligned in the magnetic field 16 of a rotating magnet to produce a convex spherical optical effect. The circle formed by the first composition 14A exhibits a color change from gold to green in reflected light when the article 22 is tilted, and exhibits a color change from blue to red in transmitted light. In addition, the article 22 includes a third composition 46 comprising a liquid medium and a magnetizable color-changing opaque pigment 44, wherein the third composition 46 is printed on the first composition 14A and / or surrounded by the first composition 14A in the form of a euro symbol. The third composition 46 also exhibits a color change from gold to green. However, the chromaticity of the third composition 46 is higher than that of the first composition 14A because the magnetizable color-changing opaque pigment 44 in the third composition 46 is opaque, while the translucent magnetic pigment 12 in the first composition 14A is translucent. At a normal observation angle, as shown in FIG. Figure 14 As shown, the Euro symbol is barely visible because both the translucent magnetic pigment 12 and the magnetizable color-changing opaque pigment 44 reflect the same gold color.

[0063] like Figure 15 As shown, the appearance of the article 22 changes when the article 22 is tilted with its upper edge away from the viewer 28. The circle printed with the first composition 14A changes its color to light green, while the euro symbol printed with the third composition 46 changes to bright green, making the euro symbol highly visible on the light background formed by the ink having the translucent magnetic pigment 12.

[0064] like Figure 16 As shown, when light source 20 is behind article 22, the color (first, second, third, fourth, etc.) of article 22 changes. Light source 20 illuminates article 22 from behind. Light 26 passes through first composition 14a, which is in the form of a circle and is blue (the first color in transmission), to observer 28. Light 26 is blocked by third composition 46, which includes magnetizable color-changing opaque pigment 44, which is the euro symbol. Observer 28 perceives the euro symbol as a black outline on a blue circle background. As the viewing angle is changed by tilting article 22, the blue circle background, i.e., first composition 14A, gradually changes its color to red (the second color in transmission).

[0065] Also disclosed is a method of making an article, comprising providing a substrate 18; and depositing a first composition 14A on a first surface of the substrate 18, wherein the first composition 14A comprises a liquid medium and a translucent magnetic pigment 12. The method may further comprise depositing a second composition 14B on a second surface of the substrate 18, opposite the first surface. The method may further comprise depositing a third composition on the first composition, wherein the third composition comprises a liquid medium and a magnetizable color-shifting opaque pigment. The first composition exhibits a first color in reflection and a second color in transmission. The first composition 14A, the translucent magnetic pigment 12, and the second composition 14B are as described above with respect to the article 22.

[0066] From the above description, it will be appreciated by those skilled in the art that this teaching can be implemented in various forms. Therefore, although these teachings have been described in conjunction with specific embodiments and examples thereof, the true scope of this teaching should not be so limited. Various changes and modifications may be made without departing from the scope of this paper's teaching.

[0067] The scope of this disclosure should be interpreted broadly. It is intended that this disclosure discloses equivalents, devices, systems, and methods for implementing the devices, activities, and mechanical actions disclosed herein. For each device, article, method, device, mechanical element, or mechanism disclosed, it is intended that this disclosure also encompasses and teaches equivalents, devices, systems, and methods for practicing the many aspects, mechanisms, and devices disclosed herein in its disclosure. In addition, this disclosure relates to coatings and their many aspects, features, and elements. Such devices can be dynamic in their use and operation, and this disclosure is intended to cover equivalents, devices, systems, and methods for using the manufactured devices and / or optical devices, as well as many aspects consistent with the description and spirit of the operations and functions disclosed herein. The claims of this application should also be interpreted broadly. In its many embodiments, the description of the invention herein is essentially merely exemplary, and therefore, variations that do not depart from the main purpose of the invention are intended to be within the scope of the invention. Such variations should not be considered to depart from the spirit and scope of the invention.

Claims

1. An article comprising: substrate; and A composition on the substrate comprises a liquid medium and a translucent magnetic pigment, wherein the translucent magnetic pigment comprises a translucent metallic magnetic material and a dielectric material serving as an optical interference cavity.

2. The article of claim 1, wherein the substrate is a polymer substrate or a paper substrate having a transparent window.

3. The article of claim 1, wherein the composition is a first composition on a first side of the substrate; and further comprising a second composition on a second side of the substrate opposite the first side.

4. The article of claim 3, wherein the first composition comprises a first translucent magnetic pigment, the second composition comprises a second translucent magnetic pigment, and the first and second translucent magnetic pigments are different.

5. The article of claim 1, wherein the dielectric material of the translucent magnetic pigment can be present in multiple layers.

6. The article of claim 5, wherein a plurality of layers of dielectric material alternate with layers of metallic material.

7. The article of claim 1 , wherein the translucent magnetic pigment appears a first color in reflection and a second color in transmission.

8. The article of claim 4, wherein the first translucent magnetic pigment exhibits a first color in reflection and a second color in transmission, and the second translucent magnetic pigment exhibits a third color in reflection and a fourth color in transmission.

9. The article of claim 1, wherein the article further comprises a third composition comprising a liquid medium and a magnetizable color-changing opaque pigment.

10. The article of claim 9, wherein the third composition is present on at least one of the substrate and the first composition.

11. The article of claim 10, wherein the substrate comprises a transparent window, and the first composition is on the transparent window, and the third composition is on the first composition.

12. The article of claim 10, wherein the substrate comprises a transparent window, and the third composition is on the transparent window, and the first composition is on the third composition.

13. A method of manufacturing an article, comprising: providing a substrate; and A first composition is deposited on a first surface of a substrate, wherein the first composition includes a liquid medium and a translucent magnetic pigment.

14. The method of claim 13, further comprising depositing a second composition on a second surface of the substrate opposite the first surface.

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