ES2985561T3 - Security film or document that has one or more enhanced watermarks - Google Patents

Abstract

The invention generally relates to a security sheet or document having one or more enhanced watermarks. In an exemplary embodiment, the inventive security sheet or document is a single-ply paper that is formed from a paper layer including one or more watermarks, and a micro-optical security device (e.g., a patch or thread) that at least partially covers a top or front portion of the watermark(s). The overlying patch or thread increases the durability of the watermark(s), thereby allowing the watermark(s), as well as areas of reduced fiber density therein, to be larger, and further allowing the areas of reduced fiber density to be thinner. In a preferred embodiment, the micro-optical security device projects one or more synthetic images that coordinate with or link to the watermark design(s). In a more preferred embodiment, the micro-optical security device offers a detectable/machine-readable feature in the form of enhanced IR brightness, especially when measured in transmission. As will be readily appreciated, the inventive security sheet or document offers greatly improved forgery resistance. (Automatic translation with Google Translate, no legal value)

Description

DESCRIPTION

Security film or document that has one or more enhanced watermarks

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. Patent Application Ser. No. 12/997,390, filed Feb. 23, 2011, and claims benefit of and priority from U.S. Provisional Patent Application No. 61/911,141, filed Dec. 3, 2013, U.S. Provisional Patent Application No. 61/911,831, filed Dec. 4, 2013, U.S. Provisional Patent Application No. 61/911,885, filed Dec. 4, 2013, and U.S. Provisional Patent Application No. 61/924,000, filed Jan. 6, 2014.

TECHNICAL FIELD

The invention relates generally to a security sheet or document having one or more improved watermarks.

BACKGROUND AND SUMMARY OF THE INVENTION

Security papers are used for the manufacture of security documents such as banknotes, passports, postage stamps and the like. Conventionally, a variety of security features are incorporated into or arranged on the surface of such security papers. Known examples of such security features include watermarks, embedded and windowed security threads, fluorescent pigments and the like.

Watermarks, which are recognizable images or patterns on paper that appear as various shades of lightness/darkness when viewed by transmitted light or by reflected light on a dark background, have provided protection against counterfeiting of security documents for hundreds of years. In fact, watermarks and their attractive designs are the most widely recognized security feature available to the general public for the authentication of security documents such as banknotes.

There is, however, a persistent need to improve the security or tamper resistance of watermarked security documents.

The present invention addresses this need by providing improved and therefore more forgery-resistant watermarks on paper and paper-like materials. Specifically, the present invention features a security sheet or document having one or more improved watermarks, as defined in independent claim 1.

Other embodiments are indicated in the dependent claims.

The film-like or foil-like security element preferably has a different color from the watermark(s) and the surrounding paper thereby enhancing the appearance of the underlying or overlying watermark(s) as well as improving the contrast between the underlying or overlying watermark(s) and the surrounding paper.

In one such embodiment, the film-like or foil-like security element(s) is (are) a micro-optical security device that projects one or more synthetic images such as the MOTION® micro-optical security device described, for example, in U.S. Patent No. 7,333,268. Such devices display colored images on a transparent or tinted background and are thus suitable for use in combination with underlying printed information. It has been observed that such security devices appear to provide the watermark(s) with a multi-tonal appearance. As will be readily appreciated by those skilled in the art, multi-tonal watermarks present an even greater challenge to a counterfeiter.

In a preferred embodiment, the micro-optic security device is in the form of a surface-applied patch covering all or part (e.g., half) of a watermark, the watermark containing one or more polymers or resinous materials within the first and/or second region of the watermark, the one or more polymers or resinous materials having a refractive index or combined (final) refractive index substantially similar to that of cellulose. In such an embodiment, the region(s) also contain one or more features selected from the group of areas of higher fiber density in the form of recognizable or discernible indicia, one or more color-imparting substances, and one or more second-level security features that are machine detectable or machine readable (e.g., ultraviolet or infrared reactive, luminescent, thermochromic, photochromic, electrochromic, metallic, or magnetic security fibers, markers, planchettes, dyes, pigments).

As will be readily appreciated by those skilled in the art, the micro-optic security device may also be in the form of a band, strip, vein, or elongated security thread applied to the surface, or a partially embedded band, strip, vein, or elongated security thread that is present in windowed regions of a second paper layer (i.e., windowed thread).

Micro-optical devices such as the MOTION® device may be designed such that, when aligned with the watermark(s), the synthetic images thereby projected are combined with the design of the watermark(s). For example, in the embodiments mentioned above, the synthetic images generated by each patch may be coordinated or merged with the watermark design(s). The synthetic image(s) may also complete the watermark design(s) or be located within the design(s). As will be explained in more detail below, this may be a one-sided or two-sided feature.

In another embodiment, the micro-optic security device(s), also described, for example, in U.S. Patent No. 7,333,268, display(s) color images (of any color, including black and white) or a translucent or substantially opaque background of a different color. In this embodiment, the micro-optic security device(s) at least partially cover and visually camouflage the top or front of the one or more watermarks, or the bottom or back of the one or more watermarks. The watermark(s) is(are) not visually discernible in reflected light from the covered side of the paper layer, but is visually apparent in reflected light from the uncovered side of the paper layer, and in transmitted light from both sides of the paper layer.

An inherent benefit in exemplary embodiments of the present invention that employ a partially or fully overlying or underlying foil-like or film-like security element, such as the MOTION® security device, is the increased durability of each watermark. As is well known to those skilled in the art, one of the primary requirements of banknotes and other security documents is that the document and its security features must withstand the effects of circulation. These documents/features must be durable (i.e., resistant to damage from bending, tearing, and soiling) and resistant to moisture and chemical absorption. Covering all or part of the watermark(s) with an applied film, foil, band, strip, streak, thread, or patch serves to physically protect the watermark(s) from damage during circulation and handling, thereby increasing its durability.

Due to the increased durability imparted to these watermarks, it has been determined that these watermarks can be made larger and that the total area within each watermark occupied by regions of reduced fiber density (i.e., first regions) can be increased and that these regions can be made thinner. Specifically, it has been found that these regions of reduced fiber density can be made at thicknesses as low as 10 to 15 microns, with total thicknesses ranging from about 10 to about 60 microns. The total area occupied by these regions of reduced fiber density within each watermark ranges from about 5 to about 75 percent (%) of the total area of the watermark, preferably from about 20 to about 60%. Furthermore, the total area occupied by each watermark within a banknote measuring approximately 10,000 square millimetres (mm2) can vary between about 5 and about 25%, denoting an increase in size compared to conventional watermarks of approximately 5%.

The present inventors have also made the surprising discovery that micro-optical devices such as the MOTION® device can also offer a machine-readable/detectable feature in the form of infrared-enhanced brightness, especially when measured in transmission. The term "infrared-enhanced brightness" as used herein is intended to refer to infrared transmission levels of at least 5% greater than (preferably greater than 10% than) the infrared transmission levels of the background paper. Infrared transmission levels can be measured by using an optical sensor with a sensitivity equal to or greater than 830 nanometers (nm) and by projecting an infrared light source with a wavelength greater than 800 nm through the sample. In order to make the infrared glow a reliable, machine-readable feature, it is preferred that the micro-optic device be manufactured using one or more infrared transparent elements (e.g., an infrared transparent ink) and not contain infrared absorbing elements (e.g., infrared absorbing inks). It is also preferred that no infrared absorbing elements be present in areas near the device on the front and back of the paper layer(s). In one such embodiment, the micro-optic device is a security thread (e.g., a MOTION® security thread) that does not contain infrared absorbing elements. In this embodiment, the micro-optical security thread is made using an infrared transparent ink (e.g., an ink comprising non-IR absorbing pigments and/or dyes) for microprinting and areas on the front and back of the paper layer(s) for at least two-thirds (2/3) of the length of the security thread that do not contain IR absorbing elements.

In addition to the at least partially overlying or underlying micro-optic device, one or more additional security features may be contained on or within the first and/or second region of the one or more watermarks. In one such embodiment, the watermark(s) do not contain one or more polymers or resinous materials within the first and/or second region. The additional security features are selected from the group of areas of increased fiber density in the form of recognizable or discernible marks, one or more color-imparting substances, and one or more second level security features that are machine detectable or machine readable, as described above.

In a second exemplary embodiment, the security paper of the invention is a multi-ply paper comprising:

a first layer of paper having a reduced basis weight (e.g., between about 10 and about 50 grams per square meter (g/m2)) and including one or more watermarks, each surface of the first layer of paper showing either the top or front of the one or more watermarks or the bottom or back thereof; and

a second layer of paper having a reduced basis weight (e.g., between about 10 and about 50 g/m2) and optionally one or more through windows, the second layer of paper covering the surface of the first layer of paper showing the top or front of the one or more watermarks or the surface showing the bottom or back of the one or more watermarks.

In one such embodiment, the second paper layer has windows, the one or more through windows of the second paper layer being aligned with the top or front or the bottom or back of the one or more watermarks. By means of this second exemplary embodiment, the use of two paper layers and optionally one or more overlying or underlying windows allows for increased contrast between the one or more watermarks and the background. The one or more overlying or underlying windows act in a manner similar to that of an electrotype, occupying regions with no paper or regions of thinner paper resulting in regions brighter than the background in each paper/watermark region.

In a third exemplary embodiment, one or more security elements in the form of one or more color-imparting substances are contained within the first and/or second regions of the one or more watermarks. The one or more color-imparting substances include dyes and pigments (e.g., ultrafine particle size pigments). In this embodiment, the security sheet or document does not include one or more film-like or foil-like security elements. The resulting watermarks have a hue (i.e., color scheme or range of tones) in a different color or shade than the bulk region of the material surrounding the watermark. The watermarks of the invention serve to increase the perceptibility and simulation resistance of existing watermarks.

In a fourth exemplary embodiment, one or more polymers or resinous materials are contained within the first region(s) and optionally the second region(s) of the one or more watermarks. As before, the security sheet or document in this exemplary embodiment does not include one or more film-like or foil-like security elements. The first and/or second region in this embodiment may also contain one or more security features selected from the group of areas of increased fiber density in the form of recognizable or discernible indicia, one or more color-imparting substances, and one or more second level security features that are machine detectable or machine readable, as described above.

In a fifth exemplary embodiment, the security sheet or document of the invention is a single-ply paper comprising:

a layer of paper that includes one or more watermarks; and

one or more transparent or translucent areas in the paper layer surrounding each watermark, thereby interweaving and enhancing the visual perception of the watermark(s).

Other features and advantages of the invention will become clear to one skilled in the art from the following detailed description and the accompanying drawings.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, shall prevail. In addition, the materials, procedures/processes and examples are illustrative only and are not intended to be limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure may be better understood with reference to the following drawings. Components in the drawings are not necessarily to scale, emphasis instead being placed on clearly illustrating the principles of the present disclosure. Although exemplary embodiments are described in connection with the drawings, there is no intent to limit the present disclosure to the embodiment(s) described herein. Rather, it is intended to cover all alternatives, modifications and equivalents.

The particular features of the invention described are illustrated by referring to the accompanying drawings in which:

Figure 1 is an image of a watermark (shield with the number 30) with a MOTION® security patch overlying or within an example security paper viewed in daylight (reflected light in the visible spectrum) and under transmitted infrared light from the visible or front side of the security paper, with the watermark and patch shown at an enlarged scale for clarity;

Figure 2a is another image of the watermark of Figure 1 with overlying security patch again viewed in daylight (reflected light in the visible spectrum) and under transmitted infrared light from the visible side of the security paper, the image enlarged but to a lesser extent than Figure 1, while Figures 2b-d are enlarged images of the same watermark with the overlying security patch shown in transmitted infrared light from the back side of the security paper (Figure 2b), in reflected infrared light from the visible side of the security paper (Figure 2c), and in reflected infrared light from the back side of the security paper (Figure 2d);

Figure 3a is another image of the watermark of Figure 1 with an overlying security patch viewed in daylight (visible spectrum reflected light) from the face side of the security paper, the image enlarged but to a lesser extent than Figure 1, while Figures 3b-d are enlarged images of the same watermark with the overlying security patch shown in reflected light of the visible spectrum from the back side of the security paper (Figure 3b), in transmitted light of the visible spectrum from the face side of the security paper (Figure 3c), and in transmitted light of the visible spectrum from the back side of the security paper (Figure 3d);

4 is a schematic diagram of a modified dual filament or Fourdrinier papermaking machine whereby watermarks are incorporated along the machine direction of a forming paper web through a nip roll cylinder, and whereby a security element in the form of an elongated security thread is applied to a surface of the watermarked paper web prior to the wet press section of the machine. The machine employs means for machine direction alignment of the watermarks and the elongated security thread on the paper web. This method of making the inventive web does not shift the fiber distribution, resulting in a higher fiber distribution with increased substrate density and stiffness that resists security thread deformation, distortion and bending;

5 is a schematic diagram of another modified Fourdrinier or twin filament papermaking machine through which an elongated security thread is introduced onto a surface of the fibrous web at or just prior to the incorporation of the watermark(s) and prior to the wet press section of the machine. The machine employs a means for machine direction alignment of the elongated security thread and the watermark(s) on the fibrous web. This process for making the fibrous web of the present invention results in the fiber flowing around the thread, resulting in a lower density fiber distribution with reduced density and stiffness under the thread applied to the surface;

Figure 6 is a schematic diagram of a papermaking machine comprised of two cylinder paper machines connected together by a collecting felt, where an elongated security thread contacts a watermarked paper web formed by one cylinder paper machine before being attached to a second paper web formed by the other cylinder paper machine. This machine also employs means for aligning the elongated security thread and the watermark(s) to the first paper web in the machine direction;

Figure 7 provides, in a side-by-side comparison, enlarged images of a prior art watermark and an exemplary embodiment of the improved watermark of the invention, having a strikingly bright or intense appearance;

Figure 8 provides, in a side-by-side comparison, enlarged images of an exemplary embodiment of the watermark of the invention employing a second-level UV-excitable security feature in both transmitted light and under UV light;

Figures 9a, b are schematic drawings showing a process for manufacturing an exemplary embodiment of the paper security document of the present invention;

Figure 10 is an enlarged image of a wet fiber mat or sheet on a papermaking machine (viewed in reflected light against a dark background) with paper removed in selected areas of the sheet with a resulting reduction in fiber density in those selected areas. The selected areas are circular in shape and are shown in two different sizes, with the larger selected areas also containing a circular region of increased fiber density; and

Figure 11a, b are enlarged images of the encircled selection area shown in Figure 10 (viewed in transmitted light) after treatment with one or more polymers or resinous materials having a refractive index or combined refractive index substantially similar to that of cellulose. The first enlarged image (Figure 11a) shows the circular region within the selection area having a color similar to that of the surrounding fiber mat or sheet, while the second enlarged image (Figure 11b) demonstrates that the printed material viewed under this exemplary embodiment of the security element of the invention is clearly legible.

DETAILED DESCRIPTION OF THE INVENTION

By the present invention, watermarks formed on or within a security sheet or document are improved, making the security sheet or document more resistant to counterfeiting.

The sheet or document of the invention, as indicated above, comprises: a fibrous sheet material that includes one or more watermarks; and means for enhancing the one or more watermarks by making them visually enhanced, detectable/readable by a machine, or both.

Fibrous sheet materials suitable for use in the present invention are paper or paper-like sheet materials. These sheet materials, which are single-ply or multi-ply materials, may be made from a range of fiber types including synthetic or natural fibers or a blend of both. For example, these sheet materials may be made from fibers such as abaca, cotton, linen, wood pulp, and blends thereof. As is well known to those skilled in the art, cotton and cotton/linen or cotton/synthetic fiber blends are preferred for banknotes, while wood pulp is commonly used in non-bank security documents.

Watermarks may be formed on fibrous sheet material using known procedures and techniques. For example, watermarked sheet material may be produced on a cylinder-die papermaking machine (using a patterned wire mesh, or by applying a thin piece of metal, usually in the form of an image or letter, to the wire mesh), or on a Fourdrinier papermaking machine (using a nip roll).

Next, some example embodiments of the security sheet or document of the invention in which various means are employed to improve the watermark(s), and their respective manufacturing processes, will be described.

In a first exemplary embodiment, the security sheet or document of the invention is a single- or multi-ply paper comprising (a) a first paper layer including one or more watermarks, each surface of the paper layer showing either the top or face of the watermark(s) or the bottom or back thereof, (b) one or more film-like or foil-like security elements having a different color from the watermark(s) that at least partially cover the top or face or the back of the watermark(s), and optionally (c) a second paper layer having a reduced basis weight compared to the first paper layer (e.g., between about 10 and about 50 g/m2) and optionally one or more through windows, the second paper layer covering either the top or front or the bottom or back of the watermark(s).

The film-like or foil-like security element(s) used in the practice of the present invention are limited only by their film-like or foil-like structure, with contemplated structures having overall thicknesses ranging from about 15 to about 100 microns (preferably, from about 15 to about 50 microns). The film-like or foil-like structures may take any form, including, but not limited to, bands, strips, streaks, threads, or patches. They may display or project information that is humanly perceptible either directly or with the aid of a device and/or incorporate information that is machine-detectable/readable. The structures may be segmented into regions, with the information being displayed or projected or otherwise contained in some or all of these regions that are the same or different.

Suitable film- or foil-like security elements may employ one or more of the following: demetalized or selectively metalized regions or layers, magnetic, combined magnetic and metallic, or embossed (e.g., blind embossing), color-shifting coatings made of color-shifting, iridescent, liquid crystal, photochromic and/or thermochromic materials, coatings of luminescent and/or magnetic materials, holographic and/or diffractive security features, and micro-optical security features.

In a preferred embodiment, the security element(s) is (are) a micro-optical structure. As noted above, such structures project one or more synthetically magnified optical images, and generally comprise: (a) a light-transmissive polymeric substrate; (b) an array of image micro-icons positioned on or within the polymeric substrate; and (c) a microlens array. The icon and microlens arrays are configured such that when the icon array is viewed through the microlens array, one or more synthetically magnified optical images are projected. These projected images may exhibit a number of different optical effects. Such structures are described in U.S. Patent No. 7,333,268 to Steenblik et al., U.S. Patent No. 7,468,842 to Steenblik et al., U.S. Patent No. 7,738,175 to Steenblik et al., International Patent Publication No. WO 2005/106601 A2 to Commander et al., and International Patent Publication No. WO 2007/076952 A2 to Kaule et al. In one such embodiment, a micro-optic structure is employed as described in U.S. Patent No. 7,333,268 to Steenblik et al. (e.g., the MOTION® micro-optic security device), the structure being formed from a polymeric substrate prepared using one or more essentially colorless polymers selected from the group including, but not limited to, polyester, polyethylene, polyethylene terephthalate, polypropylene, polyvinyl carbonate, polyvinylidene chloride, and combinations thereof.

In a more preferred embodiment, the micro-optical security device is in the form of a surface-applied patch covering all or part (e.g., half) of a watermark, the watermark containing one or more polymers or resinous materials within the first and/or second regions thereof, the one or more polymers or resinous materials having a refractive index or combined (final) refractive index substantially similar to that of cellulose. The first and/or second region of the watermark may also contain one or more features selected from the group of areas of higher fiber density in the form of recognizable or discernible indicia, one or more color-imparting substances, and one or more second level security features that are machine detectable or machine readable, as described above.

In another more preferred embodiment, the micro-optical security device is in the form of an elongated strip or thread applied to the surface, or a partially embedded elongated security strip or thread that is present in windowed regions of a second layer of paper (i.e., windowed thread). The strip or thread in this embodiment covers all or part of the watermark(s).

In an even more preferred embodiment, the micro-optical security device (e.g., the MOTION® device) is designed such that, when aligned with the watermark, the synthetic images thereby projected are combined with the watermark design. For example, in the above-mentioned embodiments, the synthetic images generated by each patch or thread may be coordinated or joined with the watermark design. The synthetic images may also complete the watermark design(s) or be located within the design(s). This may be a one- or two-sided feature. In other words, the complete information intended to be conveyed to the viewer is not provided by the watermark or the synthetic image(s) alone, but requires that both be viewed simultaneously. In one such example, when viewed at the optimal viewing angle (perpendicular) using transmitted visible spectrum light, the MOTION® patch projects a synthetic image in the form of an overlay that overlays (aligns) the shield-shaped watermark design. When the viewing angle is moved out of alignment, the synthetic image and watermark design are no longer aligned with each other, and the watermark design (shield and number 30) would be seen within the patch and the synthetic image would transition or change from the overlay to, for example, a matrix of numbers.

An inherent benefit in exemplary embodiments of the present invention that employ a partially or fully overlying or underlying foil-like or film-like security element, such as the MOTION® micro-optical security device, is the increased durability of each watermark. Covering all or part of the watermark with an applied film, foil, band, strip, streak, thread, or patch serves to physically protect the watermark(s) from damage during circulation and handling, thereby increasing its durability.

Due to the increased durability imparted to these watermarks, it has been determined that these watermarks can be made larger and that the total area within each watermark occupied by regions of reduced fiber density (i.e., first regions) can be increased and that these regions can be made thinner. Specifically, it has been found that these regions of reduced fiber density can be made at thicknesses as low as 10 to 15 microns, with total thicknesses ranging from about 10 to about 60 microns. The total area occupied by these regions of reduced fiber density within each watermark ranges from about 5 to about 75 percent (%) of the total area of the watermark, preferably from about 20 to about 60%. Furthermore, the total area occupied by each watermark within a banknote measuring approximately 10,000 mm2 can vary between approximately 5 and approximately 25%, denoting an increase in size compared to conventional watermarks of approximately 5%.

The present inventors have also made the surprising discovery that micro-optical devices such as the MOTION® device can also offer a machine-readable/detectable feature in the form of enhanced infrared brightness, especially when measured in transmission. In order to make infrared brightness a reliable machine-readable feature, it is preferred that the micro-optical device be manufactured using one or more infrared transparent elements (e.g., an infrared transparent ink) and not contain infrared absorbing elements (e.g., infrared absorbing inks). It is also preferred that no infrared absorbing elements be present in areas near the device on the visible side and reverse side of the paper layer(s).

Referring now to Figure 1, one such embodiment of the security sheeting or document of the invention is shown and is indicated by reference numeral 10. The micro-optical device is a MOTION® security patch 12 which contains no infrared absorbing elements. The patch 12 is positioned over a shield-shaped watermark 14 in which dark regions formed by fibers deposited more densely than the normal base fiber density (i.e., second regions) 16 occupy the outer perimeter, light regions formed by fibers deposited less densely than the normal base fiber density (i.e., first regions) 18 occupy the area within the shield design with the region occupied by the numeral 30 formed by even lighter or less dense regions. The watermark 14 with the overlying MOTION® security patch 12 in Figure 1 is shown in daylight and under transmitted infrared light, with the watermark and patch illustrated at an enlarged scale for clarity.

As will be readily apparent from viewing Figure 1, the numeral 30 is very bright as a result of the overlay patch. Here, the infrared brightness is correlated to the intensity of the infrared signal which, as noted above, is measured in transmission using an optical sensor with a sensitivity equal to or greater than 830 nm and by projecting an infrared light source with a wavelength greater than 800 nm through the sample. The infrared brightness may be controlled by the infrared properties of the ink used for microprinting the security patch 12. Microprinting in the form of micro image icons located on or within a polymeric substrate is accomplished using a printing process (e.g., inkjet, laser, letterpress, flexographic, gravure, intaglio, and dye sublimation printing processes), or by using a microstructure approach. In the latter case, the image icons would be realized as recesses or cavities in the substrate (e.g., cavities measuring, for example, between about 0.5 and about 8 microns in total depth), or as raised structures relative to the substrate (e.g., raised structures (colored or colorless) measuring, for example, between about 0.5 and about 8 microns in total height). An infrared transparent material (e.g., ink comprising pigments and/or non-infrared absorbing pigments) would be used to form the icons, for example, by printing, coating, or partially or completely filling the cavities or areas surrounding the raised structures, or forming raised structures (colored or colorless). It is preferred that areas on the face and reverse side of the paper layer(s) within a distance of about 5 millimeters from an outer edge of the patch contain no infrared absorbing elements.

Regarding the appearance of the embodiment of Figure 1, and as shown in Figures 2a-d and 3a-d:

(a) In infrared transmission or transmitted infrared light from the front or visible side of the document, the watermark (shield and number 30) and a faint overlay of the patch would be visible (see Figure 2a);

(b) In infrared transmission from the back of the document, the watermark (shield and number 30) would be seen in reverse and a darker patch overlay (see Figure 2b);

(c) In reflected infrared light from the visible side of the document, the watermark (outline only) and a faint overlay of the patch would be visible (see Figure 2c);

(d) In reflected infrared light from the back of the document, neither the watermark nor the patch overlay would be visible (see Figure 2d);

(e) In reflected light in the visible spectrum, one or more synthetic images would be visible from the face of the document, but not the watermark (or only a faint outline of the watermark) (see Figure 3a);

(f) In reflected light in the visible spectrum, from the back of the document, the watermark would appear dark (see Figure 3b);

(g) In transmitted light of the visible spectrum, from the visible side of the document, the combined image of the watermark and the one or more synthetic images would be visible (see Figure 3c); and

(h) In transmitted visible spectrum light, from the back of the document, the watermark (shield and number 30) would be visible in reverse with a color overlay of the patch, but not the projected synthetic images (see figure 3d).

As mentioned above, in addition to the at least partially overlying or underlying micro-optic device, one or more additional security features may be contained in or within the first and/or second region of the one or more watermarks. In one such embodiment, the watermark(s) do not contain one or more polymers or resinous materials within the first and/or second region. The additional security features are selected from the group of areas of increased fiber density in the form of recognizable or discernible indicia, one or more color-imparting substances, and one or more second level security features that are machine detectable or machine readable, as described above.

Reference is now made to methods or techniques for producing the first exemplary embodiment in which a fibrous sheet material with a film-like or foil-like security element is aligned in the machine direction (MD) relative to one or more watermarks contained or formed in the sheet material.

Film-like or foil-like security elements may be embedded (when in the form of, for example, a security strip or thread) in a second paper layer, or applied to a surface of the watermarked paper layer or second paper layer (when in the form of, for example, a thread or patch) using known methods and techniques. For example, security elements (with one or more adhesive layers) may be transferred to a surface of the watermarked paper layer or second layer as a transfer film using techniques including mechanical, chemical, thermal and photo-induced separation techniques. The concept of separating desired components from a supporting substrate is known in the art of holographic foil transfer, whereby a film with a release coating (i.e. a peel-off liner) is provided with coatings (e.g. optical) and adhesives, such that the coatings and adhesives may be transferred to a final substrate with the application of heat and pressure. This approach is particularly useful in applications requiring films with very thin cross-section thicknesses.

Activatable adhesives may be used to anchor or bond the film- or sheet-like security elements onto or within a surface of the fibrous web material. Suitable adhesives are not limited to and include, but are not limited to, water-, heat-, and/or pressure-activated adhesives that are activated in the secondary drying section of the paper machine where temperatures range from 100°C to 160°C. These coatings may be applied as solvent-based polymer solutions or aqueous solutions or dispersions. Suitable dispersions are selected from the group of acrylic resin dispersions, epoxy resin dispersions, natural latex dispersions, polyurethane resin dispersions, polyvinyl acetate resin dispersions, polyvinyl alcohol resin dispersions, urea formaldehyde resin dispersions, vinyl acetate resin dispersions, ethylene vinyl acetate resin dispersions, ethylene vinyl alcohol resin dispersions, polyester resin dispersions and mixtures thereof. Machine direction alignment of security patches to watermarks contained or formed in the sheet material can be achieved by indexing the relative position of the watermark(s) to the equipment used to produce the watermark(s) on the paper sheet. The position of the watermarks is continuously transmitted to the equipment used to apply the security patches to the paper surface. Marks or indices previously applied to the carrier film used to transport the patch(es) are used to control the speed of the carrier film and therefore the patch(es), thereby ensuring alignment of the watermark(s) with the patch(es).

The alignment in the machine direction of a security thread with watermarks contained or formed in the sheet material will now be described in conjunction with Figures 4 to 6.

In Figure 4, a Fourdrinier process for producing a single layer embodiment of the fibrous web of the present invention is shown. In this process, an adhesive-coated security thread 20 (oriented such that the visible side of the security thread and not the adhesive-coated back side is a top layer) is guided along a tube 22 by a variable speed feed device 24 (e.g., a servo drive) and is urged toward a surface of an advancing partially consolidated fibrous web 26 (e.g., a fibrous slurry containing about 1 to about 10% by weight of starting material and about 99 to about 90% by weight of water) at the wet end 28 of the papermaking machine after the web 26 has been watermarked by a nip roll cylinder 30. Here, the security thread 20 may be partially or completely positioned over the watermark (i.e., layered security features) on the surface of the web 26. As will be readily appreciated by those skilled in the art, the nip roll cylinder 30 may be used to position the security thread 20 in a manner that is not a watermarked layer. 30 pressure roller may be provided with raised and/or recessed areas on its surface, which may totally or partially overlap the area on the surface of the band 26 that will be occupied by the thread 20.

It is observed that this embodiment of the method of the invention does not alter the fiber distribution around the security thread applied to the surface, resulting in a higher density fiber distribution with increased density and stiffness of the substrate that resists deformation, distortion and bending of the security thread.

As water continues to drain from the web 26, fibers form around the yarn 20 holding it in place on a front or top surface of the web 26. Upon exiting the wet end 28, the fibrous web 26 passes through the press, primary and secondary drying and calendering sections of the paper machine. While in the secondary drying section of the paper machine, the web 26 is exposed to temperatures and/or pressures sufficient to activate the adhesive coating on the security thread, causing it to firmly bond to the yarn in the fibrous web material, with the security thread continuously exposed on a front or top surface of the web material partially or completely covering the formed water mark(s) while being hidden from view on a back or bottom surface of the web material.

Directional alignment of the security thread machine 20 with the formed watermark(s) is achieved using conventional techniques commonly employed in the art. For example, and as best shown in Figure 4, an automatic alignment control system for a papermaking machine is utilized which includes the variable speed security thread advance device 24, optical sensors 32a, 32b to track alignment marks on the nip roll cylinder 30 and the security thread 20, and an encoder wheel 34 to control the speed of the paper being formed in the machine.

As the forming web 26 moves through the wet end 28 of the papermaking machine, alignment marks on the nip roll cylinder 30 and on the security thread 20 are continuously monitored by optical sensors 32a, 32b, continuously determining/monitoring the position of the security thread 20 being fed through the tube 22 and the feeder 24 and the position of the watermark relative to an edge of the forming web 26, while the speed of paper formation is controlled by encoder wheel 34. Signals are produced from the position and speed determinations, and the speed and position of the feeder 24 are regulated based on those signals so that the security thread 20 and the watermark are aligned along the machine direction of the web 26.

In another embodiment of the inventive process, shown in Figure 5, the adhesive coated security thread 20 (again oriented so that the security thread and not the adhesive coating is a top layer) is guided through the variable speed feeder 24 and optical sensor 32b and then urged toward a surface of the partially consolidated fibrous forming web 26 by the nip roll 30 at the wet end 28 of the papermaking machine, with the nip roll 30 simultaneously or subsequently incorporating a watermark into the web 26. It is seen that, by this embodiment of the inventive process, the fiber flows around the security thread, resulting in a lower density fiber distribution with reduced substrate density and stiffness beneath the thread.

In a similar manner to that indicated above, as the forming web 26 moves through the wet end 28 of the papermaking machine, alignment marks placed on the nip roll cylinder 30 and on the security thread 20 are continuously monitored by the optical sensors 32a, 32b, thereby continuously determining/monitoring the position of the watermark(s) and the position of the security thread 20 applied to a surface of the web 26 relative to an edge of the forming web 26, while the speed of the paper being formed is controlled by the encoder wheel 34. Signals are produced from the position and speed determinations, and the speed and position of the feed device 24 are regulated based on those signals so that the security thread 20 and the watermark(s) are aligned along the machine direction 26.

A roll molding process for making a two-ply embodiment of the fibrous web of the present invention is shown in Figure 6. In this process, which employs two roll paper machines 36a, 36b connected together by a take-up felt 38, two paper webs 40, 42 are simultaneously formed, compressed together in the area of the roll 44, and then introduced together into the press, dryer, and calender sections of the paper machine. The resulting fibrous web has the same physical characteristics as those noted above for webs made using a Fourdrinier process. As will be readily appreciated by those skilled in the art, although Figure 6 shows wet-bowl type roll paper machines, dry-bowl type roll paper machines may also be used to make the fibrous web of the present invention.

The two-ply paper web 46, formed by the cylinder paper machines shown in Figure 6, has an adhesive-coated security thread 20 embedded therein and one or more watermarks formed on a surface thereof, with the security thread 20 and the watermark(s) fully visible from this surface. The watermark(s) are formed on the paper web 40 by the forming cylinder 48 and then the security thread 20 is integrated into the paper web by directing the thread through the variable speed feeder 24 and past the optical sensor 32b and then between the roller 50 and a surface of the paper web exiting the cylinder paper machine 36a. Here, the security thread 20 may be placed partially or completely over the watermark(s) on the surface of the paper web. The paper web 40 with the surface-applied security thread 20 and the watermark(s) is then directed between the roller 44 and a surface of the second paper web 42 exiting the cylinder paper machine 36b, where the two paper webs are compressed together. The second paper web 42 is homogeneous and serves to hide any irregularities in the paper formation on a back or bottom surface of the first paper web 40 that may have been caused by the presence of the thread 20.

As mentioned above, the forming cylinder 48 may be provided with raised and/or lowered areas on its surface, which may fully or partially overlap the area contacted by the wire 20 during manufacturing.

As in previous embodiments, directional alignment of the machine between the security thread 20, the watermark(s), and the paper web 40 is achieved by means of the variable speed security thread advance device 24, optical sensors 32a, 32b to track alignment marks on the forming cylinder 48 and the security thread 20, and an encoder wheel 34 to track the speed of the paper being formed on the cylinder paper machine 36a.

Upon exiting the calendering section of any of the above-mentioned papermaking machines, the fibrous web material of the invention may be wound up and stored or fed directly into another machine (e.g., a printing machine) for further processing.

In a second exemplary embodiment, the security paper of the invention is a multi-ply paper comprising:

a first paper layer having a reduced basis weight (e.g., between about 10 and about 50 g/m2) and including one or more watermarks, each surface of the first paper layer showing either the top or front of the one or more watermarks or the bottom or back thereof; and a second paper layer having a reduced basis weight (e.g., between about 10 and about 50 g/m2) and optionally one or more through windows, the second paper layer covering the surface of the first paper layer showing the top or front of the one or more watermarks or the surface showing the bottom or back of the one or more watermarks.

In one such embodiment, the second paper layer is windowed, with the one or more through windows in the second paper layer being aligned with the one or more watermarks. As with this second exemplary embodiment, the use of two layers of paper and, optionally, one or more overlapping through windows allows for greater contrast between the one or more watermarks and the background.

In a third exemplary embodiment, one or more security elements in the form of one or more color-imparting substances are contained within the first and/or second region of the one or more watermarks. The one or more color-imparting substances include both colorants and pigments (e.g., pigments with an ultra-fine particle size). As noted above, in this embodiment, the security document or sheet does not include one or more film-like or foil-like security elements. The resulting watermarks have a hue (i.e., color combination or range of shades) in a different color or tone than the bulk region of the material surrounding the watermarks, which serves to increase their perceptibility and resistance to simulation.

Watermarks have traditionally been the same colour as the paper substrate on which they are supported or within the paper. These marks are formed by a localised variation in the thickness of the paper which varies the opacity of the paper, making the watermark visible in transmitted light or in reflected light on a dark background.

A standard or prior art watermark is shown in Figure 7 against the same colored paper substrate. Here, only a marginal contrast between the light and dark areas of the watermark is apparent, making the watermark more difficult to detect. By way of comparison, as also shown in Figure 7, the improved watermark of the present invention, which includes one or more color-imparting substances in the form of one or more visible (colored) pigments (i.e., blue), has an improved quality in that the contrast between the light and dark areas in the watermark is significantly greater. Therefore, the public's attention is more easily focused on the watermark of the invention which increases the effectiveness of this security feature.

Another exemplary embodiment of the present invention is shown in Figure 8. Here, the watermark of the invention contains a second level security feature in the form of a UV-excitable substance in addition to one or more color-imparting substances. The watermark of the invention not only shows a sharp contrast between light and dark areas in transmitted light, but also contains a substance that can be excited by UV radiation, it also demonstrates a UV-responsive hue that is difficult to reproduce, making this watermark embodiment even more resistant to counterfeiting.

Referring now to Figure 9, in an exemplary embodiment where the security sheet or document is a paper security document, the inventive method of making the security document involves making a continuous roll of watermarked paper 52 on a papermaking machine 54 (Figure 9a), watermarks or watermark regions 56 repeating across the paper (Figure 9b), each having lighter weight areas (i.e., first regions) and heavier weight areas (i.e., second regions), to provide lighter and darker areas in the watermark regions 56, the method comprising:

applying a color solution 58 comprising color-imparting substances to the plurality of watermark regions 56 on one side of the continuous roll of paper while applying vacuum to an opposite side of the paper to draw the applied color solution into the paper,

wherein the higher weight areas of the watermark regions 56 contain more color-imparting substances while the lower weight areas contain less color-imparting substances, thereby providing the hue of the watermark regions in a different color or shade than that of the bulk regions of the paper surrounding the plurality of watermark regions repeating along the length thereof.

As indicated above, watermarks are formed by well-known techniques, for example on a cylinder-moulded papermaking machine or a Fourdrinier papermaking machine (using a nip roll). A variety of fibre types may be used to make the paper, including synthetic or natural fibres or a mixture of both.

The "color solution" used to impart hue to the watermarks of the present invention comprises the one or more color-imparting substances mentioned above, including both dyes and pigments (e.g., ultrafine particle size pigments).

After forming watermarks on the paper machine 54, the colored solution 58 is applied locally to the watermark regions 56 of the paper while the paper is still wet and on a forming wire and before any wet pressing occurs. The colored solution may be applied to the watermarked paper web 52 using a low volume intermittent shower with nozzles 60 aligned with the watermark regions of the paper. The colored solution is introduced into the paper web using one or more vacuum boxes 62. Although two vacuum boxes are shown in Figure 9b, one or more vacuum boxes may be used in practicing the process of the invention.

In a fourth exemplary embodiment, which will be referred to as a "transparent" watermark embodiment, one or more polymers or resinous materials are contained within the first region(s) and optionally the second region(s) of one or more watermarks. As noted above, the security sheet or document in this exemplary embodiment does not include one or more film-like or sheet-like security elements. The first and/or second region in this embodiment may also contain one or more security features selected from the group of areas of higher fiber density in the form of recognizable or discernible indicia, one or more color-imparting substances, and one or more second level security features that are machine detectable or machine readable, as described above.

The transparent watermark embodiment of the present invention provides an easily recognizable public security feature for first level authentication. The watermark(s) of the invention, which may be a paper feature, enables authentication by its transmission properties. The inclusion of such a translucent or transparent region within a security document (e.g. banknote) cannot be replicated with subsequent scanning, image analysis and digital reproduction techniques.

In an exemplary embodiment, the transparent watermark(s) of the invention is/are obtained as part of the papermaking process during sheet formation in the wet state. For example, a paper web is produced continuously on a Fourdrinier papermaking machine. The paper is deposited from a headbox onto a continuously moving wire mesh. Water from the paper is drained through the wire mesh exiting a dewatered wet fiber mat.

The transparent watermark(s) of the invention are formed by first removing paper material from selected areas of the fiber mat with a resulting reduction in fiber density (see Figure 10). This may be done using conventional techniques such as nip roll (or cylinder vat) technology. The selected areas with lower fiber density (i.e., first regions) exhibit reduced opacity compared to other areas of the watermarks (i.e., second regions) and other areas of the fiber mat (i.e., base sheet), although not transparent. The first and optionally second regions of the watermark(s) are then treated with one or more polymers or resinous materials selected for a final refractive index that closely matches cellulose (e.g., UV-curable, electron beam curable, or heat-curable polymer or resinous material).

The first and second regions may be treated with the one or more polymers or resinous materials on the papermaking machine, in an off-line web process such as rewinding or take-up, in a dedicated off-line web process prior to sheet slitting, or in individual sheets.

The one or more polymers or resinous materials, which saturate the paper in the first and optionally the second region of the watermark(s) (replacing air in the interstices between the fibers), may optionally be applied in a pattern over these areas, and may be further cured through radiation, thermal/catalytic, or oxidative means.

As best shown in Figures 11a,b, transmission of visible light through the resulting translucent or transparent watermark(s) is now possible. As a result, printed material viewed under the transparent watermark(s) is clearly legible.

The choice of a polymer or resin material(s) of appropriate modulus may also allow embossing applications to be made in translucent or transparent areas, for example, prior to printing, or during an intaglio printing process.

The transparent watermark(s) of the invention may also include one or more features within its perimeter selected from the group of areas of higher fiber density in the form of recognizable or discernible marks, one or more color-imparting substances, and one or more second-level security features that are machine detectable or machine readable, as described above.

These features in the form of, for example, fibres or planchettes may be added by random addition to the papermaking composition, or selectively placed in-line at the position of the transparent security element. Additionally, or alternatively, such inclusions could be concentrated in specific cross-direction areas of the paper.

In a fifth exemplary embodiment, the security sheet or document of the invention is a single-ply paper comprising:

a layer of paper that includes one or more watermarks; and

one or more transparent or translucent areas in the paper layer surrounding each of the one or more watermarks, thereby interweaving and enhancing the visual perception of the watermark(s).

Such patterned areas may be formed in the watermarked paper layer by treating the areas surrounding each watermark with one or more transparent polymer or resinous materials, such as a UV-curable, electron beam-curable, or thermally curable polymer or resinous material.

These screen-like areas may be treated with the transparent material(s) on the papermaking machine, in an offline web process such as rewinding or take-up, in a dedicated offline web process prior to sheet slitting, or in individual sheets.

Transparent materials saturate the paper in the applied areas by replacing the air in the interstices between the fibers. These materials may be curable or non-curable. The treated areas of the watermarked paper layer allow the transmission of visible light, meshing and enhancing the visual perception of the watermark(s).

Although various embodiments of the present invention have been described above, it is to be understood that these have been presented by way of example only, and not of limitation. The scope of the present invention is limited only by the appended claims.

Claims (11)

1. Security film, comprising: a fibrous sheet material; a watermark pattern formed within at least one layer of the fibrous web, the watermark pattern surrounded by a surrounding region, the watermark pattern comprising a first region with a first fiber density and a second region with a second fiber density, wherein the first fiber density is lower than a fiber density of the surrounding region, and wherein the second fiber density is greater than the first fiber density of the surrounding region; means for enhancing the watermark design by making the watermark design visually enhanced, detectable or machine readable, or both; and a security element comprising a micro-optical structure, the micro-optical structure comprising: a light-transmissive polymeric substrate; an arrangement of image icons located on or within the polymeric substrate; and a microlens arrangement, wherein the image icon arrangement and the microlens arrangement are configured such that, when the icon arrangement is viewed through the microlens arrangement, one or more synthetically magnified optical images are projected. 2. The security sheeting of claim 1, wherein the fibrous sheet material comprises one or more layers of fibers selected from the group consisting of abaca fibers, cotton fibers, flax fibers, wood pulp fibers and synthetic fibers. 3. Security film according to claim 1, wherein the micro-optic structure at least partially covers an upper or front portion or a lower or back portion of the watermark design. 4. Security film according to any one of claims 1 to 3, wherein the micro-optical structure comprises an infrared transparent ink, the infrared transparent ink comprising at least one non-infrared absorbing pigment or dye. 5. Security film according to claim 4, wherein the micro-optical structure is machine readable. 6. The security sheeting of claim 1, wherein the micro-optic security structure is anchored or bonded on or within a surface of the fibrous sheet material by an activatable adhesive, the activatable adhesive being selected from the group consisting of acrylic resin dispersions, epoxy resin dispersions, natural latex dispersions, polyurethane resin dispersions, polyvinyl acetate resin dispersions, polyvinyl alcohol resin dispersions, urea formaldehyde resin dispersions, vinyl acetate resin dispersions, ethylene vinyl acetate resin dispersions, ethylene vinyl alcohol resin dispersions, polyester resin dispersions, and mixtures thereof. 7. The security film of claim 1, further comprising one or more transparent or translucent areas surrounding the watermark design. 8. The security film of claim 7, wherein the one or more transparent or translucent areas surrounding the watermark design are formed of a transparent polymeric or resinous material. 9. Security film according to claim 1, wherein the micro-optical structure comprises one or more infrared transparent elements and non-infrared absorbing elements. 10. The security sheet of claim 1, wherein the security sheet is a multi-ply paper, wherein a first paper layer includes the watermark design and a second paper layer having a reduced basis weight compared to the first paper layer of between about 10 and about 50 grams per square meter, the second paper layer covering either the top front or the bottom front of the watermark. 11. Security film according to claim 1, wherein the micro-optical structure comprises a polymeric substrate of one or more colorless polymers.