KR20090066091A - Provision of frames or borders around pigment flakes for covert security applications - Google Patents

Abstract

A plurality of pigment flakes are provided to protect the symbol of flakes in the process for separating flakes from a temporal supporting substrate. A plurality of pigment flakes comprise a frame of the periphery circumference restricted by a wall and a domain inside the frame, wherein the height of the at least frame wall is Fh or more, the domain inside the frame has the mark restricted by at least one groove having a depth less than Id formed in the inside, and Fh > Id.

Description

Provision of frames or borders around pigment flakes for covert security applications}

FIELD OF THE INVENTION The present invention generally relates to thin pigment flakes, and more particularly to providing a border or frame around taggent flakes used in coating compositions and at least one groove within the framed area of the flakes. to the provision of a label as defined by (groove); More specifically, the present invention provides a frame and a marker having a frame, wherein a grooved frame is less robust and easier to break than a grooved indicia.

Specialty pigments have been developed for security purposes such as anti-counterfeiting means printed on banknotes, packaging of valuables, sealing of containers, and the like, and also for applications such as direct application to commercial items. For example, the US $ 20 federal reserve note now uses optically variable inks. The number "20" printed on the lower right corner of the front face of the banknote changes color depending on the viewing angle. This is an exposed anti-counterfeiting device. The color-shifting effect is not copied with a normal color copier, and the recipient of the bill can obscure the authenticity of the bill by observing that the bill includes the color shift security feature.

Other valuable documents and objects use similar means. For example, iridescent pigments or diffractive pigments are used in paints or inks that are applied directly to the seals used in articles or articles, such as securities, passports, packaging of original products, and the like. However, as counterfeiters continue to elaborate, security features are required that make them more difficult to forge.

One anti-counterfeiting method is to use fine symbols on multiple color shifting pigment flakes. The symbol is formed on one or more layers of the multilayer color shifting pigment flake layer by local changes in optical properties such as reflectivity. Multi-layered color shift pigment flakes generally comprise a Fabry Perot type structure having an absorbing layer separated from the reflective layer by a spacer layer. The reflective layer is typically a layer of metal, which makes the pigment flakes inherently opaque. If a large portion of this type of pigment flake is mixed with other pigments, the resulting color will be significantly different from the pigment, and if too little of these flakes are mixed with other pigments, it will be difficult to find them.

Another technique uses flakes having an epoxy-encapsulated shape of polyethylene terephthalate (PET). The reflective layer is deposited on a PET roll, and the PET is then cut into pieces. To improve the durability of the reflective layer, the flakes are coated or encapsulated with epoxy. Such flakes are available in a variety of shapes such as square, rectangular, hexagonal, and “apostrophe”, and allow for the selection of reflective metal hues such as silver, pewter, gold, and copper. However, the epoxy layer and relatively thick PET substrates (substrates typically have a thickness of at least 13 microns (0.5 mils) for use in vacuum deposition processes) typically produce relatively thick flakes greater than 14 microns. Unfortunately, such thick flakes are undesirable for use in concealment applications where the thickness is substantially greater than the base pigment. Similarly, such thick flakes do not flow well in ink and produce lumps in paint. If the paint contains thick flakes that produce a rough surface, a relatively thick and clean topcoat is typically applied on the rough surface.

It is desirable to mark the object with a concealment anti-counterfeiting device that overcomes the limitations of the techniques discussed above.

The present invention relates to the provision of a flake having a tagent or concealed symbol stamped inside, embossed or etched by a mechanical device, or formed by a laser device, wherein the concealed symbol is a microscope. Can be observed. In order to preserve the integrity of the symbol, a frame is provided around all or some concealed symbols so that when individual flakes are removed from the support structure on which the flakes were deposited, most flakes are in a less controlled and unpredictable manner. Instead of being destroyed as a result, it is broken along the provided frame line, otherwise the fracture line will occur very often around and through the symbol. To further ensure that the break is made along a frame line or groove, the frame groove may have a different profile than the groove defining the bleeding symbol, and the frame groove may be more easily broken or destroyed than the concealed symbol groove. It is designed to crack. In some examples, parallel frame lines may be provided such that the flakes are broken into ribbons; In one preferred embodiment of the invention, the flakes, more particularly one or more symbols within the flakes, have a border with grooves framed on at least four or less sides around the one or more symbols. As such, the flakes will break down into a uniform square or rectangle along the frame line. In this way, of course, a triangular or hexagonal lamella can also be provided by pre-framing the symbol on three sides before removing the lamella from the substrate. Conventional release layers are provided so that the flakes are easily removed from their backing layer or support layer and the flakes can be peeled along the frame line upon removal. Frames can be created in a similar way to how symbols are created; Using a laser or etching or stamping a film on a substrate; In a preferred embodiment the frame is provided in the same process as the formation of a symbol.

Hereinafter, the term “embossed flakes” is used to apply pressure to the flakes with an embossing tool or by coating on the embossed substrate to form a substrate formed on the embossed substrate. By embossing means embossed flakes.

It is therefore an object of the present invention to provide a flake having a symbol thereon, wherein the symbol is molded from the flake or embossed temporary support to protect the symbol during the process of separating the flake from the flakes temporary support substrate. It had or had an embossed, etched or laser formed frame or rim in the flakes, said frame groove being deeper and / or more prone to breakage than the groove defining the mark or symbol inside the frame.

It is an object of the present invention to provide a frame groove having a cross-sectional profile different from the cover groove, wherein the frame groove is designed to be more easily broken or cracked than the cover groove.

In another aspect of the invention, the substrate is pre-metalized prior to adding the release layer. After the flakes are separated from the release layer, the embossed substrate can be cut into reflective flakes rather than reused to provide another batch of coated flakes. The pre-metalized substrate can be cut into longitudinal strips to create a new security device (ie, thread) with the same matching design as the flakes produced with the substrate.

In another aspect of the invention, after separation from the substrate and after a suitable post process for producing shaped / symbolized flakes, the “sized” flakes are destroyed during printing and painting applications. It is encapsulated to improve the durability of the flakes against.

According to the present invention, a plurality of pigment taggent flakes is provided, each flake comprising a frame around its periphery defined by a wall and an area within the frame, the one or more said frames The height of the wall is greater than or equal to F _h , and the area inside the frame has a depth I _d formed therein. Having a label defined by one or more grooves that are less than F _h > I _d .

According to another aspect of the present invention, a substrate embossed with a plurality of frame grooves having a depth F _h defining a frame, and a plurality of indicia grooves forming a mark inside each frame. Provided is a sheet of tangent area for forming a sheet of tangent flakes, wherein the depth of the marking groove is I _d. Less than F _h > I _d Subsequently, when the sheet or coating on the sheet is separated into tangent flakes, breakage occurs more along the frame grooves than the label grooves.

According to another aspect of the invention, the carrier; A coating composition is provided comprising a plurality of single layer inorganic dielectric concealed tangent flakes dispersed in the carrier, the flakes being enclosed in a frame, an identifiable symbol formed in an area within the frame, the frame wall being It is deeper than the wall of the groove defining the identifiable symbol.

According to another aspect of the present invention, there is provided a method for producing a flake having a label thereon, the method comprising: providing a substrate coated with a release layer; Providing at least one optical coating on the release layer; Engraving a label in the form of one or more symbols on the plurality of areas on the optical coating, wherein the engraved label is in the form of one or more grooves formed inside the optical coating; In each area, engraving a grooved frame around the mark, the grooved frame being deeper than one or more grooves forming the mark; Removing the optical coating from the release layer such that the coating is broken into flakes in the form of a labeled frame along the grooved frame.

In another aspect of the present invention, there is provided a lamella having at least one symbol thereon, the lamella having a laser formed or embossed grooved frame, which has been previously etched into the support sheet before they are separated from the support sheet, or A frame or border that separates from adjacent flakes by being separated from adjacent flakes along the rim, and which defines the periphery of the flake is more susceptible than one or more symbols thereon.

According to another aspect, the present invention provides a plurality of embossed pigment concealed tangent flakes coated with a light transmissive non-conforming coating that reduces the depth of the grooves inside the flakes.

I. Overview

Concealed security flakes are generally invisible to normal observation. Inspection techniques such as overhaul under a microscope or analytical techniques such as elemental analysis are used. In one embodiment, the opaque flakes comprising a label (eg, a particular shape) substantially match the visual characteristics of the bulk pigment or other material mixed with the flakes. In certain embodiments, a single layer of inorganic opaque flakes having a selected shape is mixed with iridescent mica-based flakes or other base pigments. In this specification, "single layer" of inorganic material is meant to include multiple layers of the same inorganic material stacked on each other.

Inorganic concealment flakes are particularly preferred when heat, solvent, sunlight, or other factors destroy the organic flakes. For example, inorganic concealed flakes used in explosives can be found even after exposure to high temperatures and / or pressures and are difficult to destroy even in such environments. The flakes according to an embodiment of the present invention are also considerably thinner than conventional shaped flakes, typically less than about 10 microns, which can be used in inks and provide a smooth surface finish in paint to provide a separate clean finish. No need to use In addition, the thin inorganic flakes according to the embodiment of the present invention are similar in density to base pigment flakes prepared using similar techniques. Thick flakes mixed in an organic substrate are often of different densities than thin film base pigment flakes and may segregate before or during use while the carrier is in fluid. Segregation of flakes is undesirable, but if segregation of flakes occurs, the composition ratio of concealed flakes and base flakes in the composition is not constant, and if the concentration of the concealed flakes becomes excessively high due to segregation, the concealment of the concealed flakes is lost. Because.

II. Exemplary Opaque Flakes

1 is a plan view of a portion of a document 10 having security features 12 in accordance with one embodiment of the present invention. At least a portion 14 of the security concealment feature 12 is printed with ink or paint containing opaque flakes (hereinafter referred to herein as "hiding flakes") containing a label, mixed with a bulk pigment. . In one embodiment, the concealed flakes have a particular shape, such as, for example, square, rectangular, trapezoidal, "diamond" shape, rounded shape, and the like. In another embodiment, the concealed flakes comprise a grid pattern with or without a selected shape. Preferably, the embossed, etched or laser-selected shape is provided to form a frame or border so that the flakes are destroyed along the frame or border when removed from the temporary support substrate. In certain embodiments, the grating pattern comprises grating intervals that are optically inactive in the visible range of the spectrum. That is, such a grating pattern does not form a visible diffraction grating. Also, concealed flakes are often referred to as taggent flakes, but not all targent flakes are always concealed flakes.

In general, bulk pigment particles comprising bulk pigment flakes are amorphous. In one embodiment, the concealed flakes can be distinguished from the bulk pigment flakes by their shape. On the other hand, the bulk pigment flakes have a primary selected shape and the concealed flakes have a secondary selected shape. The production of pigment flakes having a shape can be accomplished by depositing the flake material on the substrate using a patterned substrate and separating the flake from the substrate to obtain a pattern such as a frame or border, or by using a laser or other means. It can be achieved by a variety of techniques, such as the technique for cutting the patterned flakes from. The selected shape of the concealed flake may be associated with, for example, the manufacturing facility, date of manufacture, or other feature of the document 10, or ink used in the process of manufacturing the document, for example.

Roll coaters are a type of device used to make concealed flakes of selected shapes or irregularities in accordance with embodiments of the present invention. A roll sheet of polymer based material (also known as a “web”) passes through the deposition zone (s) and is coated with one or more thin layers. A roll of polymeric substrate can be passed through the deposition zone several times in the forward and reverse directions. The thin film layer (s) is then separated from the polymeric substrate and processed into flakes. Other devices or techniques can also be used.

In general, it is desirable to limit the total thickness of the thin film layer deposited (and subsequently removed) from a roll of polymeric membrane substrate to less than 10 microns. PET is a type of polymer membrane substrate used in roll coaters, and PET membrane substrates generally have a thickness of about 13 microns or more. The thinner the PET film, the more prone to thermal deformation in the vacuum deposition process. Both the heat of the deposition zone and the heat of condensation of the deposited thin film layer (s) increase the temperature of the polymer substrate as it passes through the deposition zone. Thus, the minimum thickness of the flakes cut from the PET film and forming the PET film is 13 microns.

In addition, the flakes have a selected shape formed by embossing a frame on the substrate, wherein the flakes are separated and broken along the frame, and the concealed flakes are one or more symbols bordered within or by the frame and / or grid pattern, the other It includes a form label. The lattice pattern is embossed or otherwise formed on the substrate used in the roll cutter before depositing the thin film layer to be processed into flakes. In another embodiment, a selected amount (percentage) of the deposition substrate surface area is embossed in a lattice pattern or shape pattern such that the thin film layer is separated from the deposition substrate and processed into flakes to obtain a selected amount of concealed flakes. . This technique provides concealed flakes with the same optical design (composition and thickness of the thin layer) as the base flakes. For example, if 10% of the surface of the deposited substrate is embossed in a lattice pattern and / or a shape pattern, a pigment mixture containing about 10% of the concealed flakes can be obtained as shown in FIG. Different deposited substrate rolls may vary the percentage of embossed areas on the substrate surface to provide pigment mixtures containing different amounts of concealed flakes, or emboss in different patterns to obtain different shapes and / or patterns.

2A is a schematic diagram of a portion of a deposition substrate comprising an embossed portion 13 and an unembossed portion 15. The embossed portion has a frame, which frame is exaggerated for illustration purposes, and the embossed portion optionally or optionally, for example comprises a grid or a symbol, and the unembossed portion is essentially Smooth Alternatively, the non-embossed portions are embossed in different frames, grids, or symbols. The surface area ratio of the embossed portion 13 to the non-embossed portion 15 is a tangent flake (provided from the embossed portion) having the same thin film structure as the base flake (made from the unembossed portion). ) By the selected amount. The deposition substrate 11 is moved from one roll 17 through an deposition zone (not shown) in the roll coater to another roll 19, although other embodiments use different types of substrates and deposition systems. FIG. 2B is a schematic view of a portion of another deposition substrate 11 ′ having an embossed portion 13 ′ and an unembossed portion 15 ′.

Pigment flakes with identification labels, although readily observable, provide security features; However, if pigment flakes with identification labels are not readily observable, the counterfeiter may not even know that concealed flakes are present. One embodiment of the present invention uses a concealed pigment flake having the same optical characteristics as the base pigment. The concealed pigment flakes are not visible to the naked eye, but can be seen in magnifications on the order of 50 × to 1000 ×. Concealed pigment flakes having essentially the same visible characteristics can be mixed with the base pigment in a wide range of proportions without significantly affecting the color of the composition. In some embodiments, the concealed pigment flakes are readily available in compositions containing 5-10 weight percent and 95-95 weight percent, respectively, of concealed pigment flakes and base pigment flakes with similar appearance (eg color and / or color shift). Is discernible. Often, shaped opaque concealed flakes are readily identifiable in the field using a handheld microscope (eg, a "shirt-pocket" microscope) and can be identified with smaller magnifications than similarly sized flakes containing symbols.

Another approach is to use opaque concealed flakes having a selected shape with a different color than the base flakes. In one embodiment, the opaque concealed flake is a bright metallic (silver) flake having a thin layer of aluminum or other reflector between layers of dielectric material such as MgF ₂ . Bright flakes generally have high reflectance over a wide range of visible light wavelengths and often do not have characteristic colors. Bright flakes made of gold and copper can, for example, be yellow and red in color. Shaped (eg diamond-shaped) bright flakes can be added to the colored base pigments from about 0.25% to about 5% by weight without changing the color, but the bright flakes are still illuminated by 50 ×. ) Is easily identifiable by magnification (ie, 50x magnification). Under dimmed magnification, the shape and high brightness of the flake distinguishes it from the base flake. When the shaped thin flakes are used at less than 0.25%, they are diluted by the base flakes, so that the shaped bright flakes are almost invisible in the field of view, and as a result, the concealed flakes are difficult to be identified.

When the amount of light flakes exceeds about 5% by weight, certain types of flakes, especially dark flakes, change color (eg color tone). In this case, too bright flakes essentially "dilute" the color of the base pigment. However, even if light flakes having a single type of shape are added in small amounts to many other types (color and / or color shifting) pigment flakes, a relatively small amount of the bright flakes also provide concealment security features. Therefore, it is very preferable to use the bright flake which has a shape in the composition containing a color shifting pigment. Similarly, if the composition containing the pigment and the bright flakes is not intended to displace or is indistinguishable from a composition containing 100% of the pigment flakes, the dilution of the color is not important.

Pigments are often mixed with carriers to form paints or inks. Examples of the carrier include polyvinyl alcohol, polyvinyl acetate polyvinylpyrrolidone, poly (ethoxyethylene), poly (methoxyethylene), poly (acrylic) acid, poly (acrylamide), poly (oxyethylene), Poly (maleic anhydride), hydroxyethyl cellulose, cellulose acetate, poly (polysaccharides) such as gum arabic and pectin, poly (acetals) such as polyvinylbutyral, polyvinyl chloride and polyvinyl chloride (Vinyl halides), poly (dienes) such as polybutadiene, poly (alkenes) such as polyethylene, poly (acrylates) such as polymethyl acrylate, poly (methacrylates such as polymethyl methacrylate ), Poly (carbonates) such as polyoxycarbonyl oxyhexamethylene, poly (esters) such as polyethylene terephthalate, poly (urethanes), poly (siloxanes), poly (sulfur) Such as ids), poly (sulfones), poly (vinylnitriles), poly (acrylonitriles), poly (styrene), poly (2,5-dihydroxy-1,4-phenyleneethylene) Poly (phenylenes), poly (amides), natural rubbers, formaldehyde resins, other polymers, and mixtures of polymers and polymers containing a solvent.

FIG. 3A is a schematic plan view of a portion 14a of the concealment feature 14 shown in FIG. 1. In order to observe the shape of the flakes whose diameter is typically about 5-100 microns, more typically about 20-40 microns, the portion 14a of the concealment feature is typically at an enlargement of about 20 × to 300 ×. Shown. The security feature was printed using an ink containing base pigment particles 16 and a concealed pigment flake 18 having a selected shape (in this case a "diamond" shape). The optical characteristics and concentration of the concealed pigment flakes were chosen so as not to interfere with the visible appearance of the composition made from the base pigment particles.

Base pigment particles 16 are shown as amorphous flakes. As an alternative, the base pigment particles have a selected (ie regular) shape. Similarly, the concealed pigment flake 18 may comprise a grating. Forgery can be made more difficult by adding a lattice further. In some embodiments, the concealed flakes 18 generally have the same optical characteristics as the base pigment particles. As an alternative, the concealed flakes 18 have different optical characteristics than the base pigment particles, but use sufficiently small amounts so as not to harm the visible appearance of the composition made of the base pigment particles.

In certain embodiments, the "diamond-shaped" concealed flakes were diagonally bright flakes of about 25 microns x 35 microns. The flakes having this shape emboss a diamond pattern on a roll of PET immersion base material, and then use a standard thin film design for bright flakes (e.g., 100-60 nm Al between MgF ₂ layers each about 400 nm thick). It is prepared by dipping. The total thickness of the bright flakes is around 900 nm, which is about 1 micron. The embossed pattern is also known as a "frame" (as opposed to the lattice intended to make the pattern in or on the lamella), which is embossed in some embodiments and engraved in other embodiments. Apart from the diamond flakes themselves, which provide some measure of the concealment feature when distributed in a predetermined proportion with other irregular flakes, the diamond shaped flakes are embossed as additional concealment symbols, thereby providing two steps available to protect the device. Can provide concealment features.

Combining the metal layer and one or more dielectric layers makes it easier to remove the flakes from the deposited substrate. Thin film stacks with only dielectric layers are brittle and often receive residual stresses during the deposition process. Such thin film stacks break more randomly and as a result, fewer shaped flakes. Since the metal is relatively soft, an all-metal stack or monolayer is difficult to process into patterned flakes along the frame of the deposited substrate. In certain embodiments, metal-dielectric and dielectric-metal-dielectric flakes having a thickness between about 0.5 microns and about 3 microns provide an excellent combination that can simultaneously exhibit ductile and brittle properties to separate from the substrate. Excellent flake patterns are obtained when processed. In certain embodiments, the shaped bright flakes, having a total thickness of about 1 micron of soft metal layer between brittle dielectric layers, produce diamond-shaped flakes in about 90% yield from an embossed deposition substrate. .

The thin film layer is separated from the deposition substrate and processed into flakes using conventional techniques. The embossed diamond pattern provides a line so that the thin film layer is broken into flakes having a selected diamond shape along the line. In another embodiment, the diamond-shaped flakes are about 12 microns x 16 microns and comprise a grating on most of the surface of the flakes. The grating is nominal 2000 lines / mm and does not provide significant diffraction effects in the composition when used as a target. The shape of the 12 × 16 micron flakes is easily seen at 100 × magnification; However, at this magnification the grating is not easily visible. The grid is easy to see clearly at 400 × magnification. In other embodiments, the grating is more coarse and easily visible with the same magnification (eg, 50 × 100 ×) that is used to fractionate the shape of the tangent flakes. As such, the gratings used to provide security features to the tangent flakes need not be optically active in the visible region of the spectrum.

In certain embodiments, the base pigment particles are flakes of mica coated with a layer of TiO ₂ or other dielectric material. Coating materials typically have an indicator of relatively high reflectance. Mica is a natural mineral that is relatively inexpensive and easily processed into flake substrates. When the mica flake substrate is coated with a high indicator material layer having a selected thickness, nacreous pigment flakes are obtained. Mica flake substrates can be coated with several optional materials using a variety of methods. Such pigments are commonly known as "mica based" pigments. The picture of the image printed with such a pearlescent pigment looks different from the original, so mica-based pigment flakes are preferably used as an exposed security feature. However, it is impractical to shape the mica flake substrate or to provide a symbol on the mica flake substrate. Concealed flakes according to embodiments of the present invention are mixed with mica based pigments such that concealed security features can be included within an image printed with mica based pigment flakes. Shaped pigment flakes, made from a single layer of an inorganic dielectric material such as TiO ₂ or ZnS, have concealed pigment flakes of a quarter wavelength optical thickness ("QWOT"; quater-wave optical thicknes) at wavelengths in the visible light spectrum. If the thickness is about five times, the appearance is similar to that of the mica pigment. Typically, single layer ZnS concealed flakes intended to conform to the appearance of mica based pigments have a thickness of about 60 nm to about 600 nm. Processing fully-dielectric flakes from an deposited substrate having an embossed diamond-shaped pattern tends to yield lower yields than the corresponding metal dielectric flakes.

3B is a schematic cross-sectional view of a bright pigment flake 20 according to one embodiment of the invention. Reflective layer 22 is present between two dielectric thin film layers 24, 26. The dielectric thin film layers 24, 26 provide firmness to the bright pigment thin film 20, making it easy to remove the pigment flakes from the roll coater substrate. In order to provide a composition that dries or cures to a smooth surface, it is desirable to keep the bright pigment flakes below 10 microns thick. In certain embodiments, the flakes are between 1 micron and 3 microns thick. Since the flakes are very light, the thinner the flakes, the more difficult it is to process and handle, and the thicker the flakes, the stronger, the harder the flakes are to break along the frame pattern.

Reflective layer 22 is typically a high reflectivity metal thin film layer, such as aluminum, platinum, gold, silver, or copper, or a moderate reflectance metal thin film layer, such as iron or chromium. The reflective layer 22 is thick enough to be opaque (reflective) in the visible region of the spectrum, but not so thick that it makes it difficult to separate the thin film layer from the substrate to produce the flakes. In other words, too thick metal reflective layers tend to provide a flexible layer between the relatively fragile dielectric layers 24 and 26, making it difficult to process the deposited layer into flakes. Preferred materials for use in the dielectric layer include ZnS, MgF ₂ , SiO ₂ , Al ₂ O ₃ , TiO ₂ , Nb ₂ O ₅ and Ta ₂ O ₅ , among other materials. In some embodiments, dielectric thin film layers 24 and 26 also provide environmental protection for reflective layer 22.

The bright flakes 20 have a selected shape and include optically or optionally other marks, such as surface (lattice) patterns or element fingerprints. At sufficiently low concentrations, the bright flakes 20 are added to colored pigments and colored compositions (eg inks and paints). Shaped bright flakes may be added to the base (ie, amorphous or of other shapes) bright flakes as a concealment security feature.

3C is a schematic cross section of a bright lamella 20 ′ comprising an elemental indicator layer 28. The bright flake 20 'includes reflective layers 22', 22 "between the dielectric layers 24 ', 26', and the layer 28 providing the elemental label. A layer made of a material not found inside the base flakes where bright flakes are used together, secondary ion mass spectrometry ("SIMS"), energy dispersive X-ray ("EDX") and Auger analysis; In addition, the elemental label is present inside the concealed flakes, not the base flakes, and the difference can be easily observed by micro-SIMS, micro-EDX or micro-agent analysis. It is not possible to overcome this security feature by simply adding a labeling element to the pigment mixture (eg by adding a compound containing the elemental label to a small amount of carrier).

The element label layer 28 is not optically active since it is between two opaque reflective layers 22 ', 22 ". The reflective layers 22', 22" are made of a material used for base flakes such as aluminum. It is chosen to be made of the same material. Preferred materials for use in elemental labels include, among others, platinum, iridium, osmium, vanadium, cobalt, and tungsten. It is well known to those skilled in the art that the elemental labeling material selected depends on the base pigment used together. In another embodiment, the bright flake reflective layer is made of an elemental labeling material (see symbol 22 in FIG. 3B). For example, bright or colored concealed flakes using platinum as the reflective layer are mixed with bright or colored base pigment flakes using aluminum as the reflective layer. In another embodiment, the amount of flakes containing elemental labels, mixed in the pigment mixture or composition, is determined to provide a proportion of the element selected from the pigment mixture (eg the ratio of aluminum to platinum). In another embodiment, the material of the dielectric thin film layers 24 ', 26' (FIG. 3B reference 24, 26) is selected to provide an elemental label.

3D is a schematic cross-sectional view of a color shifting pigment flake 30 according to another embodiment of the invention. Color shift pigment flakes 30 are generally known as symmetrical 5-layer Fabry-Perot interference flakes. The thin film stack 32 includes one reflective metal layer 34, two space layers 34a and 36b, and two absorbing layers 38a and 38b. Absorbent layers are generally very thin, translucent layers made of chromium, carbon, or other materials. The reflective layer, spacer layer, and absorber layer are all optically active, that is to say, they contribute to the optical performance of color shifting pigment flakes. Each face of the flakes provides a Fabry-Perot interference structure similar to incident light, so that the flakes are optically symmetrical. Alternatively, the color shift pigment flakes are three-layer flakes, such as fully-dielectric pigment flakes or absorbent layers / dielectric layers / absorbent layers.

Color Transition The color and color shift of pigment flakes is determined by the optical design of the flakes, ie the material and thickness of the layer within the thin film stack 32, which is well known in the art of optically variable flakes. The optical design of the color shifting pigment flakes 30 is typically chosen to match the optical properties of the base pigment flakes that are mixed together. The color shifting pigment flake 30 is shaped (see FIG. 3A, reference numeral 18) and optionally or alternatively includes other indicia such as surface lattice patterns and / or elemental labels.

For example, the reflective layer may include an elemental label, such as a reflective metal, different from the base pigment flakes, or may include additional elemental labeling layer (s) that are optically active or inactive (FIG. 3C, reference numeral 28). ) Reference). Alternatively or additionally, the spacer layers 36a and 36b and / or the absorber layers 38a and 38b include elemental labels. For example, if the base pigment flakes use MgF ₂ , SiO ₂ , or Al ₂ O ₃ as the spacer material, the concealed pigment flakes 30 use other spacer materials, such as TiO ₂ or ZnS. Labeling materials of the spacer layer and / or the absorber layer include elements that are readily observed using elemental analysis.

In some embodiments, the use of different spacer materials and / or reflective materials causes the concealed flakes 30 to have different optical properties than the base flakes. For example, if the concealed flakes and the base flakes have a similar color in normal incident light, the color shift may be different. In general, low indicator spacer materials (eg, Mg ₂ F and SiO ₂ ) have a greater color shift (“fast shift” pigment) than high indicator spacer materials (eg, ZnS and TiO ₂ ). To provide. However, since most ordinary observers cannot discern the difference between a mixture and 100% base flakes according to embodiments of the present invention, even if the color shift does not exactly match the color shift of the base flakes, such concealed flakes are relatively It can be added to the base pigment flakes in high concentration.

4 is a cross-sectional view of varnish 40 containing concealed flakes 42 dispersed in a carrier, according to the present invention. The carrier was transparent or lightly colored, and the concealed flakes 42 were at a concentration selected such that they would not be observed by normal observation. Any color coating or bright (eg, "chrome") coating 46 is applied to the object 48 under the varnish 40. Varnish 40 provides concealment security features to the object without disturbing the appearance of the object. In certain embodiments, any color coating 46 is an image printed with a pearlescent or color shifting pigment to provide exposure security features to the object. The object is, for example, a document, a product, a package, or a seal. The varnish 40 may provide a concealment security feature to an object that already includes the concealment security feature, without significantly altering its appearance. For example, if a stock certificate is printed with an exposure security feature and then it is desired to provide a concealment security feature to the stock certificate, the exposure security feature may be applied to a varnish 40 or similar ink composition (ie, concealed flakes). Containing an essentially transparent ink composition). In another implementation, additional concealment security features are provided to an object that already has one or more concealment security features. In certain embodiments, the concealed flakes make up less than 2% of the varnish.

FIG. 5 illustrates a composition 50 (eg, ink or paint) comprising a base pigment flake 16 dispersed in a binder or carrier 52 and a concealed flake 18 having a shape according to another embodiment of the invention. ) Is a cross section. The concealed flakes 18 have a selected shape, or other mark, such as an element mark or surface grid pattern. The composition 50 is applied to an object 48 such as a label, product package, bank check, or consumer item.

Adding concealment flakes to existing ink or paint compositions provides concealment security features to images made with ink or paint. For example, inks containing color shift flakes provide color shift images as exposure security features on bank checks or other objects. A concealed flake according to one embodiment of the present invention is added to the ink so that the resulting mixture is used to print an image substantially similar to that printed with the original ink. Thus, an ordinary bank check observer may not notice a change in appearance of the exposure security feature (ie, color shift image) after the concealment security feature is added. The cover of the concealed flakes shows, for example, the date of manufacture, the place of printing, and / or the source (manufacturer) of the ink.

III. Experiment result

Test standards using optically variable intaglio (“OVI”) pigment flakes of magenta to green were prepared and measured. The bright and optically variable tangent samples have a lattice pattern of 2000 lines / mm, which makes it easy to distinguish (ie, locate) the targent flakes from the base pigment flakes. Made it more difficult. The grating pattern could be clearly observed at about 400 × and did not induce visible light diffraction characteristics in the image printed with the test composition. It is believed that the diffraction effect does not occur when the content of targent flakes is low and poorly oriented toward the observer. In another embodiment, a fine lattice pattern is included over the shaped tagent flakes. The shape can be confirmed by primary magnification under a microscope, but the grating pattern was not easily identified at primary magnification. Lattice patterns were observed at higher magnifications. The counterfeiter can observe the shape or symbol by microscopic examination, but the lattice pattern cannot be observed and therefore does not include the lattice pattern in the forged article, thus including such lattice pattern in the tangent flake having the selected shape or symbol. This enhances the concealment of the tangent flakes.

The first test sample ("Sample 1") is 90 (weight)% of conventional (base) magenta to green pigment flakes mixed with 10% of magenta to green OVI pigment flakes comprising a lattice ("tangent flakes"). It contained. The tangent flakes were easily observed by conventional microscopy, and because the color of the tangent flakes was in good agreement with the color of the base flakes, the color performance of the mixture was the same as the test standard. Careful management of the tangent flakes is required for close color matching, and new optical designs for each color of the tangent flakes are commonly used to match the color of each of the base flakes.

Another approach is to use a standard targent flake design with a base flake with many different colors. Bright tangent flakes using an aluminum reflective layer (giving the flakes a "silver" appearance) were also evaluated. The processing of the flakes is relatively simple and this flake was very easily observed at a concentration of 5% when mixed with the colored base pigment flakes. Bright tangent flakes are used with many colored base pigments to provide concealment security features. The amount of bright tangent flakes in the composition depends on the desired result. For example, the color performance of an intaglio blend containing 5% bright tangent flakes mixed with magenta to green OVI bases is discernible by parallel comparison with the composition of 100% magenta to green OVI flakes. Compositions that are essentially identifiable with 100% magenta to green OVI flakes use less than 5% bright flakes, such as compositions that have a bright flake concentration of about 0.25% to 3% by weight in magenta to green OVI flakes. It is believed that bright flakes may be added at a concentration of at least 5% to pigment flakes that provide a lighter and less saturated color without significantly altering the appearance of the composition. The points with the selected shape and the points with different colors (eg "silver" instead of magenta) are combined, so that even brighter concentrations of light tangent flakes are easily observed under normal magnification even at concentrations of less than 1%.

IV. Example method

6 is a flow chart of a method 600 of manufacturing a pigment flake in accordance with an embodiment of the present invention. At a selected proportion of the deposited surface area of the roll substrate, a roll substrate is provided that includes an unembossed (“smooth”) portion and an embossed portion (step 602). In one embodiment, the embossed portion is embossed into the frame such that the flakes have a selected shape. In another embodiment, the embossed portion is embossed in a grid pattern or symbol. In other embodiments, the substrate is patterned using a process other than embossing, such as laser cutting. One or more thin film layers are deposited over the roll substrate (step 604) and the deposited thin film layer (s) are processed into flakes (step 606) to produce a flake mixture containing a selected amount of tangent flakes. The yield of the tangent flakes depends on the shape in which the thin film is processed, the characteristics of the frame, lattice pattern, or symbol, and the parameters of the processing process.

For example, with reference to FIGS. 2A and 2B, if 10% of the surface of the roll substrate is embossed with a grid or symbol, the yield of targent flakes containing the grid pattern or symbol is expected to be about 10%. If 10% of the surface of the roll substrate is embossed into a diamond-shaped frame, the yield of dielectric-metal-dielectric flakes is expected to be 9%, which is the patterned portion of the thin film stack. This is because a 10% yield reduction occurs during processing. Similarly, because of the 50% yield reduction that occurs when the patterned portion of the thin film stack is processed into shaped flakes, a 5% yield is expected for the shaped fully-electric flakes.

While the invention has been described above with various specific embodiments, aspects of the invention that provide significant advantages are described below.

For example, one embodiment of the present invention that provides significant advantages is in terms of using a frame or border that frames a symbol or label framed by such a border on the substrate material used to form a coating thereon. .

Referring again to FIG. 7, there is shown a sheet comprising a plurality of euro symbols in the picture, each € symbol on the sheet having an embossed border around it. This is generally done by embossing an organic substrate, such as a PET substrate, with a framed € symbol and then coating the substrate with a detachable coating. 8 is a photograph of flakes after separation from a backing material or substrate. This picture clearly shows that most of the symbols are intact with little cracking inside or through the symbols. By using the present invention, only a very small amount of flakes in this figure are broken in such a way as to obscure the € symbol. However, as shown, after the lamella is separated from the substrate on which the lamella has been deposited, there is no frame along all sides of all the flakes. Some flakes do not include a border, and other flakes contain one to four borders. However, this can be understood. Because a frame border separates one flake from its nearest neighbor flake, when the flake is separated, the rim generally remains attached to one flake and not attached to the flake adjacent to the other side of the frame rim. Do not. However, because of the presence of a frame or border, most of the flakes are provided along the frame line, either on the side or on the other side of the frame, with uniform flakes having fractured and relatively straight edges. Often, each flake with a symbol has one or more border or frame sections attached to the flake after the flake has been separated from the web or substrate on which it was deposited. Preferably the frame is more useful than other parts of the lamella.

9 is a photograph of a plurality of Mg-Gn flakes containing μ symbols, the flakes being randomly destroyed and some symbols are preserved but other symbols are being destroyed, which is due to stress cracking due to the absence of the frame and thus apparent randomness. This is due to the rupture of the line. 9 shows stress cracks penetrating the flakes, the action of which causes the flakes to break. Moreover, cracks continue to appear inside the lamella, thereby obscuring the symbol. While providing a frame according to the present invention does not completely prevent such stress cracking, there is provided a means by which cracks can be controlled along the frame line or routed such that the cracks preferentially follow the frame, thereby controlling this crack to a significant extent. . Unlike FIG. 9, an embodiment of the present invention shown in connection with FIGS. 7 and 8 provides a method of preserving the shape and integrity of a symbol on the lamella to a very high degree by separating the flakes along a predetermined border. In general, it does not obscure the concealment symbol inside the lamella.

Cracks appearing in a frameless symbol appear and propagate in fragile dielectric materials such as glass, but within the sheet of framed symbols shown in FIG. 7 the cracks stop and change their propagation path along the provided frame line. The flake is preferably cracked along the frame line by providing a frame. Most of the cracks observed in the lamella of FIG. 8 do not penetrate the lamella completely, stop at the lamella's more elastic metal core (Al / Ni / Al) level, and are masked against the decryption of the original embossed symbol. It causes a shadowing effect.

In both of Figs. 8 and 9 flake has a layered structure of a thickness of from about 1300nm that is 1.3 _{microns, 10nm Cr / 480nm MgF 2 /} 80nm Al / 50nm Ni / 80nm Al 480nm MgF 2 / 10nm Cr. Ni is present to provide a magnetic layer for exposure characteristics.

FIG. 10 is a photograph of a plurality of framed symbols present between a plurality of flakes without any concealed symbol or frame, with a ratio of 1:10 to the other flakes of a double framed symbol. There are two interesting aspects to this embodiment. At the primary observation level by a 100 × handheld microscope, one can observe concealed flakes containing the euro symbol thereon, and also assume that the ratio of the concealed symbol to the unhidden symbol is about 1:10. In addition, to determine the authenticity, it is possible to compare the ratio of the irregular flakes of the square symbol. As such, the authenticity of the coating can be determined with a certain degree of reliability through the shape, distribution, and identification of the symbols present within the framed shape.

Even if the flake having a symbol framed by a border or frame is often broken into a desired shape along a frame line or groove, as shown in the framed flow path marker in FIG. 10, the flake embosses undesirably. There is a case of destruction along the line which was made.

With reference to FIG. 11A, a cut plane of the substrate 110 defining only a portion of the arrangement is shown, and more particularly, a portion of the region adjacent to which one complete flake and another flake can be formed. In this example embodiment, the bordered or framed flake with the letter "JDSU" and the accompanying logo is preferably broken along the frame boundary 111 such that the flake is square in shape. Or the depth of the groove 111 forming the frame 111 is considerably deeper than the groove forming the logo 112 or the letter 113. The ratio of the depth of the frame to the logo or character is preferably greater than 10: 8, preferably larger, to ensure that the flakes are destroyed and broken along the frame boundaries, ie within the frame grooves. 11B is a cross sectional analysis showing the relative depth of embossing on a substrate. The groove defining the frame is U-shaped, V-shaped and wider than the groove defining the narrow logo and text. It is desirable for the coating material to coat the substrate and form the flakes to fill more grooves of letters and logos than frame grooves. This increases the destructiveness of the frame and reduces the destructiveness along the grooves defining the letter or logo. FIG. 11C corresponds to FIGS. 11A and 11B and is a vertical view of the substrate. FIG.

In contrast to FIG. 11A, FIG. 11D is a substrate of mirror image relief, where the frame is defined by a wall and letters and logos protrude from the base of the substrate. FIG. 11E shows the relative height of this wall and FIG. 11F is a vertical view of the substrate. The logo and frame are still defined by the wall when the lamella sheet is removed from the substrate.

12A is a cross section of a prior art framed lamella wherein the grooves defining the mark in the form of a letter or logo and the grooves defining the frame are the same depth. Although a full double-walled U-shaped frame is shown to show the difference between FIGS. 12A and 12B, after the lamella is separated from the substrate, the lamella will generally not have a double-walled U-shaped frame since it must be broken along the frame channel. Dashed lines are shown to indicate where the flakes are expected to break when separated from the substrate. However, in Fig. 12A, because the groove depth is the same for the groove and for the symbol, some flakes will be cut along the symbol groove. As shown in FIG. 12B, the height or depth of the groove defining the symbol is about half the height or depth of the groove defining the frame. In other words, the frame is deeper than a symbol. This ensures that most flakes will be cut along the frame groove and not crack along the symbol groove. Generally, the ratio of the frame groove to the symbol groove is preferably 3: 2 or more, and more preferably 4: 2 or more.

The flakes of FIGS. 12A and 12B are shown to have a uniform coating, the thickness of the flakes being substantially the same on the top, bottom and sidewalls.

Impingement of the material onto the substrate in a vertical or near vertical trajectory using physical vapor deposition (PVD) coating techniques, e.g. evaporation or sputtering, results in deposition layers having the same thickness on top, bottom and sidewalls. In practice, however, PVD deposition produces atoms that are incident at oblique angles to the substrate as shown in FIG. 13B and such oblique trajectories result in deformation leading to variations in thickness. In the case of an extremely oblique orbit, the opening to the groove in the deeper groove will have a thinner coating than the bottom, which is preferred for this example with the aim of causing the flakes to break along the groove.

The higher the aspect ratio, the greater the difference between the bottom, top and sidewalls of the feature. This phenomenon is well known in the manufacture of semiconductor devices having high aspect ratio characteristics.

Destruction of the flakes can be through different mechanisms.

Abrasion is fracture produced by applying a force parallel to the surface of the flakes. Cut is fracture produced by applying shear force to the flakes. Compression or impact is fracture produced by applying a force perpendicular to the flakes. Often destruction can be due to a combination of these mechanisms. This mechanism may occur during the post-treatment of the flakes and during the coating application. For example, material milling can occur during the mixing process (particle to particle interaction and / or wear) in the liquid phase necessary to improve the uniformity of the ink and paint.

Wear and cutting, mechanically induced by mechanical shear, often occur during certain print applications where the flakes are forced through the screen. An example of this is the blade and ink in an anilox system during a flexo or gravure print application or a squeegee forcing a flake of ink to penetrate the screen. It will be an interaction. This interaction is similar to the method used in the milling method called "knife milling". In this way, the milling action is obtained by rotating the assembly using a knife or blade to cut the particles.

Impact milling can occur by high speed mechanical interaction with other flakes or using equipment used in post-treatment processes and coatings.

Nevertheless, surface irregularities will concentrate the load applied to the flakes and create non-uniform load distribution conditions.

This nonuniform load distribution is shown in FIG. 14A. There is a localized energy difference depending on the location of the tear point (area) on the flake. For example, if the failure due to abrasion is taken into account, the shear stress developed underneath the deeper features indicated by region 1 will be greater than on the underside of the shallower features shown in region 2 of FIG. 14B. In addition, as described above, the microstructure below the deep feature is more susceptible to destruction than that of the shallow feature.

Although the present invention provides a method for facilitating the breakage of the flakes along the frame line rather than the marker line or groove, the embodiments described below protect the flakes to prevent further undesired breakage after the flakes are separated from the substrate. . 15 shows the flakes encapsulated in a protective coating.

In this embodiment, the flakes are coated with a high dielectric constant material such as ZnS, TiO ₂ , SiO _x , Al ₂ O _3, etc., or the dielectric / metal multilayer flakes are semi-like, such as sol-gel (SiO _x ) which enhances the observation of the symbol. It may be coated with a transparent material. When the flakes are made of a low refractive index material of n <1.65, encapsulation of the high refractive index material, i.e., n of 1.65 or more, results in microstructured flakes having dichroic properties. This embodiment is essentially a stack of alternating high / low / high dielectric layers forming shaped / symbolized flakes with concealed functions and visible optical effects similar to pearlescent pigments.

Advantageously, the encapsulation process not only enhances the durability of the flakes but may also provide additional functionality for the microstructured flakes. In contrast to vacuum deposition techniques (PVD or CVD), it is well known that encapsulation with solgel or other wet chemistry methods is non-surface conforming. For example, it is used in ophthalmic optical coatings to mask scratches or other surface defects during the molding process of the lens.

Encapsulation by non-conforming coatings in wet chemical processes fills spaces such as grooves in the embossed flakes, reducing the non-uniform loads on the flakes that are already fragile, thereby improving fracture characteristics. Let's do it. In contrast, a conforming coating is a coating that has substantially the same thickness anywhere, regardless of the microstructure of the substrate on which the layer (s) are deposited. Inconsistent coatings, such as wet chemical coatings, will tend to "planarize" the flakes by filling gaps in the microstructure. This is very advantageous because it provides the advantage that the flakes are embossed so that the visual effects can be seen and then the flakes are flattened in a manner that preserves or augments the visual effects.

Coating embossed flakes in this manner has particular applicability to "edible flakes", eg, pharmaceutical and food industry applications. Materials used as “edible flakes”, many of which are FDA approved for consumption, include dielectric materials such as SiO _x , TiO _x , AlO _x , FeO _x . However, such materials are more fragile than metal or polymeric materials, and the inventors believe that, according to the teachings of the present invention, the frame is more susceptible to destruction than the markings inside the flakes, as is more commonly known as "edible charms" or ". It has been found that processing "edible flakes", and coating these more fragile flakes with sol-gels or other protective coatings, would be very advantageous to prevent some of the breakdown that would otherwise occur during the post-treatment process.

The improvement of fracture properties is also observed when the flakes are coated with semitransparent ductile material by the encapsulation method. In this example, the flakes are coated by deposition of a thin layer of soft polymeric semitransparent material under vacuum. One suitable deposition process is so-called plasma polymerization. This process is well known for coating SiO _x H _y , TiO _x H _y or CO _x H _y , which is a variation of Plasma Enhanced CVD (SiO ₂ , TiO ₂ and diamond-like carbon). Some polymers may also be physical vapor deposited, evaporated or even sputtered to form functional groups or to improve the durability of the microstructured concealment target.

1 is a plan view illustrating a portion of a document having security features.

FIG. 2A is a schematic diagram of a portion of a deposition substrate including an embossed portion and an unembossed portion. FIG.

FIG. 2B is a schematic view of a portion of another deposition substrate 11 ′ comprising an embossed portion 13 ′ and an unembossed portion 15 ′.

3A is a schematic top view of a portion 14a of the security feature 14 shown in FIG. 1.

3B is a schematic cross section of a bright pigment flake.

3C is a schematic cross section of a bright flake 20 'providing an elemental fingerprint.

3D is a schematic cross section of a color shifting pigment flake 30, according to another embodiment of the invention.

4 is a cross-sectional view of a varnish with opaque concealed flakes dispersed in a carrier, according to one embodiment of the invention.

5 is a cross section of a base flake and an opaque concealed flake dispersed in a binder, according to another embodiment of the invention.

Figure 6 is a flow chart for a method for producing a pigment flake according to an embodiment of the present invention.

7 is a photograph of a sheet including a plurality of Euro symbols, each symbol being framed by a square frame or border embossed on the substrate.

8 is a photograph of a plurality of Mg-Gn color transition flakes each containing a flow path symbol, most of which have a complete or partial frame surrounding the symbol.

FIG. 9 is a photograph of a plurality of Mg-Gn μ symbols on a lamella, in which the lamellas are randomly destroyed, some symbols are preserved but other symbols are broken due to a fracture line resulting from the absence of a frame.

10 is a framed plurality of symbolic photographs within multiple flakes without any concealed symbol or frame, with the ratio of framed symbols to other flakes in the photograph being 1:10.

11A is an isometric view of a cut embossed substrate showing the depth of the frame grooves inside the substrate.

FIG. 11B is a cross-sectional analysis of the substrate shown in FIG. 11A.

11C is a vertical view of the substrate of FIG. 11A.

11D is an isometric view of a cut embossed substrate showing the height of the frame wall and the logo wall protruding from the substrate.

FIG. 11E is a cross-sectional analysis of the substrate shown in FIG. 11D.

FIG. 11F is a vertical view of the substrate of FIG. 11D. FIG.

12A is a diagram of a cross section of a prior art flake of uniform coating.

12B is a view of the cross section of the lamella according to the present invention, where the frame depth is about twice the depth of the symbol.

Figure 13a is a view of the cross section of the flakes according to the invention, wherein the coating of the wall is thinner than the coating of the bottom.

13b is a view of a cross section of a flake according to the invention;

FIG. 14A is a view of the cross section of the lamella groove, wherein the coating is thicker at the top wall than at the bottom of the groove of the groove, to facilitate lamella fracture along the groove.

14B is a view of a groove defining a lamella symbol exhibiting a uniform coating thickness.

FIG. 15 is a view of a flake in accordance with the present invention, wherein the flake is encapsulated with a light transmissive protective coating.

Claims (24)

A plurality of pigment taggent flakes, each flake comprising a frame around its periphery defined by a wall and an area within the frame, the height of the at least one frame wall being at least F _h . And an area inside the frame is formed therein and has a depth of I _d. A plurality of pigment flakes having a label defined by at least one groove that is less than F _h > I _d . The plurality of pigments of claim 1, wherein each flake has an upper substantially planar surface and the wall extends downwardly from the planar surface and the one or more grooves extend downward. Flakes. The plurality of pigment flakes of claim 1, wherein the label is a symbol or logo. 2. The plurality of pigment flakes of claim 1, wherein each of the flakes has the same symbol or logo. 2. The plurality of pigment flakes of claim 1, wherein F _h / I _d is at least 1.5. The plurality of pigment flakes of claim 1, wherein each of the flakes is encapsulated in a coating. 7. The plurality of pigment flakes of claim 6, wherein the coating is selected from the group consisting of metals, metal compounds, oxides, nitrides, polymers, and cermets. The plurality of pigment flakes of claim 1, wherein the at least one groove is a V-shaped groove. The plurality of pigment flakes of claim 1, wherein the at least one groove is a U-shaped groove. The plurality of pigment flakes of claim 1, wherein the label can only be observed using a magnifying glass. 3. The plurality of pigment flakes of claim 2, wherein each of the flakes is comprised of a multilayer coating to provide visual optical effects. A sheet of tangent area for forming a sheet of tangent flakes, a) a substrate embossed to have a frame groove of depth F _h and a plurality of cover grooves inside each frame, the depth of the cover groove being I _d Less than, F _h > I _d Then the substrate breaks along the frame groove rather than the label groove when the coating on the sheet is separated into tangent flakes; or b) a substrate embossed to have an indicia wall, said frame comprising a frame wall having a height F _h and a plurality of beacon walls inside each frame, the height being less than I _d , F _h > I _d Subsequently, when the coating on the sheet is separated into tangent flakes, the fracture comprises a substrate along the frame wall rather than along the label wall. Targent Area Sheet. The target of claim 12, wherein the cross section of the frame groove has a profile different from that of the cover groove, or the cross section of the frame wall has a contour different from the cross section of the cover wall. Area sheet. 14. The tangent area sheet according to claim 13, wherein one of the frame groove and the cover groove is tapered, and the other of the frame groove and the cover groove has parallel sidewalls. The sheet of claim 12, wherein the sheet comprises a web coated with a coating, and wherein the tangent flake is formed with the coating. As a plurality of pigment target flakes, Each lamella comprises at least two frames around its side defined by a wall, and an area within the frame, wherein at least one of the frame walls is at least F _h , and the area within the frame is inside thereof. A plurality of pigment tangent flakes formed on and defined by at least one groove having a depth less than I _d , wherein F _h > I _d . A plurality of embossed pigment concealed tangent flakes coated with a light transmissive non-conforming coating that reduces the depth of the grooves inside the flakes. 18. The plurality of embossed flakes of claim 17 wherein the uncoated coating effectively flattens the flakes. 18. The plurality of embossed flakes of claim 17 wherein the non-coherent coating is a sol gel coating. 2. The plurality of pigment tangent flakes of claim 1, wherein the flakes are coated with an incoherent coating that reduces the depth of the grooves and the label is not obscured by the coating. 21. The plurality of pigment tangent flakes of claim 20, wherein the uncoated coating enhances the contrast of the label and the background so that the label is more observable. 21. The plurality of pigment tangent flakes of claim 20, wherein the pigment tangent flakes are edible flakes. 18. The plurality of pigment tangent flakes of claim 17, wherein the pigment tangent flakes are edible flakes. A foil comprising a substrate having at least one thin film layer deposited thereon loosely thereon to form flakes when removed from the substrate, the at least one thin film layer having a plurality of framed symbols formed therein to form grooves or floors; The frame around the symbol provides the lamella with a line to be separated along the line when the one or more thin film layers are removed from the substrate, the frame having a groove deeper than the symbol.

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