Security paper.

Back Paper

This invention relates to security paper for banknotes, checks and various documents. The banknotes are known to use security mechanisms, such as strips or wires made of a transparent film with a continuous reflective metal layer, of which a vacuum-coated aluminum-coated polyester film can be mentioned as the most common example. Banknotes made from such paper have been in circulation in several countries for several years. When a security mechanism is incorporated into the security paper and the paper is then printed to produce a security document, e.g., a banknote, the yarn cannot be immediately detected in reflected light, but can be detected in a dark image when the document is placed against the light.

In addition, our earlier British Patent No. 1095286 (Ottway) describes and discloses a security mechanism for security paper comprising a continuous fine security strip having a width of about 0.75 mm and overlaid with an image, writing or pattern about 0.4 mm high. Ottway security strips can be made of metal foil, which can be aluminum, and can also be in the form of a laminate. The image, writing or pattern described in Ottway's patent is very small, i.e. 0.4 mm, and the width of the mechanism is 0.75 mm. The writing of the mechanism or other printed pattern is usually not noticeable without an aid such as a magnifying glass or microscope.

To improve the security of security documents, especially banknotes, against modern counterfeiting methods using sophisticated color separation, printing and photocopying techniques, a security yarn has recently been introduced comprising a thin layer of aluminum on a plastic base British Patents Nos. 1552853 and 1604463 deal with banknotes containing such windows. Paper made according to the methods described in our European Patent No. 59056 can be used to make such banknotes.

This development has increased certainty and windowed paper has been used on banknotes in several countries. This type of banknote increases security against counterfeiting, as when the banknote is viewed against the light, the ribbon appears as a dark line, and when the other side of the banknote is illuminated, the shiny aluminum parts that appear at the windows are clearly visible. However, it is necessary to increase certainty by using more sophisticated security mechanisms in order to make it more difficult to counterfeit, as the visible, light-reflecting aluminum parts of the security mechanism can be simulated to a certain extent with modern materials and methods using e.g. foil printing.

It is an object of the present invention to further make counterfeiting more difficult by creating a security element on a windowed security paper comprising adjacent bright, contrasting colored areas in the longitudinal direction. The longitudinal edges of the element should preferably intersect the boundaries of these areas and be shaped in such a way that adjacent bright areas are visible to the naked eye as a complete register. A counterfeit in which the registration differs only somewhat from the perfect would thus also be noticeable to the uninitiated.

The invention relates to a security paper comprising at least one elongate security element which is partially embedded in the paper and parts of which are visible in windows on the surface of the paper spaced longitudinally apart, which security element is visible to the light in the transmitted light and visible in the windows and comprises a plurality of layers, comprising a support layer and metallic areas so that when the visible parts of the security element are viewed in reflected light, at least two metallic areas are visible to the naked eye in each window, forming patterns repeated in the longitudinal direction of the element. The security paper according to the invention is characterized in that the size and shape of the repeating pattern are chosen so that each window shows at least two metallic areas of different colors and giving different reflections.

Thus, reproducing the light reflection of the windowed areas of the paper requires the counterfeiter to use at least two reflective materials of different colors. This requires at least two different operations, e.g., the use of a foil press and two metallic foils of different colors. In order for a counterfeiter to be able to simulate a pattern comprising different cutting elements of a security element, e.g., aluminum and gold (see Example 1 and Figure 1), he must first print one color, e.g. aluminum from the aluminum foil to correspond to the entire length of the wire visible in the window areas and then a number of smaller gold wires on top of the aluminum areas previously made of the gold-colored foil. The registration of such machinery is incomplete, e.g. the best achievable tolerance is 0.1 mm. There will therefore be weaknesses in the registration for simulated aluminum and gold wires, which is noticeable, especially when the registration is weak in the transverse direction with respect to the security element.

The counterfeiter may seek to overcome this limitation by, for example, reducing the width of the simulated gold wires to less than the width of the aluminum wires. In this case, however, an area consisting only of aluminum can be detected at least on the other side edge of the gold wire, while in real security paper the gold wires extend to the edges of the security element.

By using precision register splitting methods to remove individual security elements from the web, the images of Figures and 7 can be applied, whereby a particular point or other identifiable portion of a monochromatic or multi-colored metal surface can be placed exactly on the edge of the security element. As a result of this falsification, the point falls either over or at the edge of another metallized color, leaving an area between the point and the edge of the simulated element; in both cases the simulation is visible to the naked eye.

The width of the security element is preferably at least 0.8 mm and more preferably between 1 and 3 mm, but wider strips can also be used, e.g. 5 or 8 mm. In cases where the width of the security element does not exceed 3 mm, the security element can be incorporated into the paper by the methods described in our European Patent No. 59056. The paper of the present invention can be produced by a wet lamination technique in which two still moist layers are joined around a security element and at least one of said layers has windows from which the security element is visible when the papers are joined. The wet lamination technique can be enhanced by the methods described in European Patent No. 229645. The dry lamination technique can be used to join two layers around a security element to produce the paper of this invention, and such dry lamination generally uses an adhesive.

In connection with the paper security element of the present invention, it is preferable to use a support layer having raised, selectively metallized areas on one side forming a repetitive pattern in the longitudinal direction of the element and a continuous metal layer on the other side of the support layer. a visible metal area in the window areas of the security paper. The security element described may have aluminum, selectively metallized areas and the continuous metal layer may be a metal of a different color. Alternatively, in another embodiment, the selectively metallized areas are aluminum and the continuous metal layer is also aluminum, and a transparent layer of color is interposed between the two layers, so that the continuous metal layer is different in color from aluminum when viewed from the selectively metallized side of the security element. The metallic regions may form a repeating pattern along the length of the element. Alternatively, one of the areas may contain numbers, letters, or other characters.

Boundaries are formed between the different colored areas, at least one of which preferably extends to one or both edges of the security element. In a preferred embodiment, all boundaries extend from one edge of the security element to another over its entire width.

In a high-value but low-use document, a so-called one-time document, it is not necessary to bind the security element to the paper it touches. Banknotes and the like, who are repeated use and consumption, however, is very desirable that the prolonged use voucher security element is attached to the paper the security element is applied to each half of the entire width of the adhesive layer.

According to the present invention, the security element to be placed on the paper may have an asymmetrical shape, in which case precision is required to ensure that the right side of the security element faces upwards and settles in the windows of the paper. However, it is not easy to ensure that the right side of the asymmetrical safety element comes up and is visible in the window. It is therefore advantageous, at least for the easy production of the paper according to the present invention, that the security element is substantially symmetrical in appearance, the element being similar on both sides before it is incorporated into the paper. An element with a symmetrical appearance does not necessarily have to be symmetrical with respect to a certain central plane, but a safety element symmetrical with respect to the central plane is very practical in the production of the paper of this invention, especially using the methods described in our European Patent No. 59056. Such a fully symmetrical security element can be formed by gluing together two security elements as described above.

In order to improve the security of the paper according to the present invention, it is preferred that each window of the paper shows at least three metallic areas of different colors, two of which may be the same color, although two more colors may also be used. The pattern displayed in the paper windows may indicate different denominations based on the colors or pattern used. In one aspect of the invention, the metallic areas visible in the windows may be special strip codes for banknotes of different denominations, the different strip codes of which are obtained e.g. by using different lengths (i.e. dimensions parallel to the security element) for different colored metallic areas.

In one aspect of the present invention, the paper uses a security element having a continuous layer of aluminum capable of reflecting incoming light and also transmitting a visually perceptible amount of light applied to said continuous layer. The continuous layer thus has transparent mirror-like properties. Typically, but not exclusively, the optical density of such a continuous metal layer is in the range of 0.15 to 1.0. The optical density should preferably be in the range of 0.3 to 0.7.

The length of the windows of the paper according to the present invention may vary and security elements of different widths may be used, but the length of the windows is preferably 2-8 mm, more preferably 3-5 mm, and the width of the security element is preferably 1-3 mm.

In the case of the security elements used in the paper according to the present invention, it is important that the reflection given by the surfaces of the metal layers is mirror-like in nature. It will be apparent to those skilled in the art that reflective surfaces must be as smooth as possible and therefore bright and shiny in order to achieve the best performance. Aluminum bonded to a substrate such as a polyester film reflects very well il

Ί and is generally recommended for the safety elements described here. However, a printed or coated metal layer in which metal particles having reflective surfaces are incorporated into a transparent polymer layer, e.g., a highly reflective metallic dye, can also be used as the reflective surface.

The invention also relates to a security document, in particular a banknote, which is produced by printing on paper according to the present invention.

The invention is described below with reference to Figures 1-7 and 7a. Each figure shows a security element suitable for making a security paper according to the present invention. In these seven figures, reference numeral 1 denotes a metallic region in which light is reflected from a dividing metal surface and which is placed on one side of a polyester film. The metallic regions 2 are selectively metallized regions that can be prepared by selectively removing metal from a continuous metal layer using methods known in the art. Examination of these seven figures shows that the metallic regions can be of different shapes, and in Figures 1, 2, 4 and 5 are preferred, since in their pattern at least two metal regions 1,2 have a boundary 5 extending to the edges of the security element. Figure 3 shows how letters can be used in a security element to form a name, such as a paper manufacturer name or a banknote denomination. In Fig. 3, however, the boundaries 5 do not extend to the edges of the security element. The repetitive patterns shown in Figures 6 and 7 are suitable for presentation to potential counterfeiters as difficult to copy patterns, but these two security elements are cumbersome as they require precise register cutting to form the security element by cutting the web into individual security elements used as strips or strips. Accurate cutting technique and accurate registration are essential to achieve the patterns shown in Figures 6 and 7. In the figure of Figure 6, not all boundaries 5 extend to the edges of the security element.

is shown, the metallic letters shown in Figures 1-2 and 4-7 can be combined in 2 readings, cf. Figure 7a.

Letters, as in the figure with other patterns, e.g. patterns thus, are used for the metallic color 1a

Figure 8 shows a piece of security paper 3 suitable for printing a banknote. In particular, Figure 8 shows three windows showing three areas of the security element, each of which has adjacent metal areas of different colors indicated by reference numerals 1 and 2. The hidden part of the security element is indicated by reference numeral 4.

The invention will now be described in more detail with reference to Figures 9, 10, 11 and 12, which illustrate longitudinal parts of the safety elements according to the invention.

Referring to Fig. 9, the upper surface of the polyethylene terephthalate (polyester) substrate 11 has metal areas 12 extending in the transverse direction of the security element. The metal areas 12 can be of any color and can be opaque or translucent in quality due to the metal in the very thin film. On top of the metal areas 12 is a lacquer layer, which may be clear or colored, and may be fluorescent, e.g. a protective layer 13 to form the areas 12 by a demetallization process. below the polyester substrate 11 is a continuous metal layer 14, which may be either opaque or translucent but which reflection should be different from the reflection regions 12, when the paper is considered the direction of the arrow. Layers 16 are adhesive layers that are preferably colorless and clear. Layers 15 and 17 are additional clear lacquer layers which may be colored and / or fluorescent. In one variation of the security element shown in Figure 9, the optical properties of layers 15 and 17 may be incorporated into layers 16, thus eliminating layers 15 and 17. The colors of layers 13, 15, and 17 (or layer 16 instead of layers 15 and 17 in the just described variant) may each vary from visible or fluorescent. depending on the lighting. Substrate 11 is preferably polyester, but other suitable polymers may be used; layer 11 may further contain a dye.

Four examples are described below with reference to Figure 9.

Example 1

The layers 16 in this example are colorless and clear and consist of an adhesive that adheres well to the paper fibers. The metallic regions 12 and the metallic layer 14 are matt aluminum having an optical density of 2.0-2.5. The metallic regions 12 are formed by demetallizing an aluminum-coated film by a known technique to obtain the pattern shown in Figure 1. Layer 11 is a clear polyester layer containing a yellow dye. The lacquer layer 15 is colorless but contains a fluorescent blue substance. The lacquer layer 17 is colorless and contains a fluorescent yellow substance. Layer 13 is clear and colorless. The security element is incorporated into the paper so that the selectively metallized areas 12 are facing up and visible in the window areas of the security paper.

The security element of this example is dimmed to transmitted light overall and when viewed from both sides appears as a continuous dark thread in the paper. But when the security element is viewed through a window in the direction of the arrow as shown by a reflected light metallic areas 12 are reflected strongly in silver and the continuous metal layer 14 in the direction of the arrow shown in parts reflected in the gold-colored and form a clear contrast with respect to the metal regions 12. In the windowless areas of the paper containing the security element shown in Fig. 9, the patterning of the element can also be observed to a certain extent depending on the metallic colors of the security element and the thickness of the fibers on it. When the paper containing the security element is viewed from the window side with ultraviolet light, the security element appears as a continuous blue line that is clear at the windows and the fluorescent substance is also detectable in the windowless areas. When the security paper is considered the arrow on the opposite side of the windowed puo10 unloaded, the security element appears as a simple strip of metal under normal light and yellow under ultraviolet light.

Example 2

In this example referring to Fig. 9, the adhesive layers 16 are clear and colorless, the selectively metallized areas 12 are matt aluminum having an optical density of 2.02.5, and the layer 14 also has a continuous layer of metallized aluminum having an optical density of 0.6 and is highly reflective but translucent. Layers 15 and 17 have not been used in this example, and the backing layer 11 is a clear polyester containing a green dye. Layer 13 is clear and colorless. The security element is incorporated into the paper so that the selectively metallized areas 12 are facing up and visible in the window areas of the security paper.

When this embodiment is viewed in visible light, a pattern, which may be as shown in Fig. 4, is seen on the windowed portion as highly reflective metallic green and silver areas with a clear contrast between them. The patterning is also noticeable in the areas of the paper where the security element is located. When the paper is viewed in reflected light visible from the windowless side, the wire appears as a simple strip of metal. When the paper is viewed from the windowless side against the light, the metallic areas 12 appear as dark areas against a green background. When the paper containing the security element according to this example is viewed from the windowed side against the light, the green reflective areas still appear bright green, while the silver reflective areas appear dark.

Example 3

In this example, layers 16 are bright and colorless.

Layers 15 and 17 are again omitted and the support layer 11 is colorless polyester. The metallized areas 12 are made by demetallizing a continuous layer of aluminum to provide the pattern of Figure 2. Layer 13 is clear and colorless. The continuous metallic layer 14 consists of vacuum-bonded copper having an optical density of 2.5. The security element is incorporated into the paper so that the selectively metallized areas 12 face up and are visible in the window areas of the security element.

The security element according to the present invention is completely opaque to transmitted light and therefore appears on the paper as a dark strip when viewed in such light. When the paper containing the security element is viewed in reflected light from the windowed side, the pattern is shown as shown in Fig. 2 with repetitive, highly reflective areas of silver and copper. This pattern is also noticeable in the areas of the paper where the security element is located. The security element, on the other hand, appears in the light reflected from the windowless side of the paper as a simple, in-paper copper strip.

Example 4

The security element of this example is as in Example 3, but with the difference that layer 13 contains a substance that fluoresces blue and ultraviolet light. When the security paper is illuminated with reflected ultra-violet light in the arrow direction, the reflected strongly in the visible light reflective areas 12 silver blue against a dark background.

A security strip useful in accordance with the present invention is shown in Figure 10. The layers 11 of this security element are each support layers. The surface of the upper support layer IIA has selectively metallized areas 12, which may be opaque or transparent. The lacquer layers 15 on each side of the security element are each individually bright or colored and can be fluorescent. The layer 14 is a continuous metallized layer, different in color from the areas 12, which may be opaque or translucent because it is a thin metal film attached to the lower support layer 11B by a vacuum. When manufacturing the security element according to Fig. 10, the support layer 11A with the metal areas 12 is joined to the lower support layer HB, on which there is a continuous metal layer 14, by using a laminating adhesive 18. The layers of the security element shown in Fig. 10 can be varied to provide different optical properties as described in Examples 1, 2, 3 and 4. The laminating adhesive 18 may, for example, be colored and the desired optical properties may be obtained by using a metal layer 14 of the type of metallic regions 12.

In this embodiment, the layer 13 may either be left in the metallized areas 12 as in Figure 9 or removed as in Figure 10. If left in place, the layer 13 may be either clear or colored with a dye or fluorinating agent.

Another security strip according to the present invention is shown in Figure 11. The support layer 11 is made of polyester. The selectively metallized areas 12 are aluminum and the layer 14 is a continuous matte metal layer that is different in color from aluminum and may be copper, gold or the like. Layer 13 can also optionally be removed or left in place in this case; it can be bright or colored.

The security element according to Figure 11 is incorporated into the security paper during manufacture so that the selectively metallized areas are upwards and visible in the windows of the paper.

Figure 12 shows a preferred security element for use in the manufacture of paper according to the present invention, in which the security element is symmetrical with respect to the central plane. This security element is formed by laminating the two security elements of Figure 11 to each other, and the lamination is enhanced by an adhesive layer 18. One of the layers 14 can optionally be removed to provide a visually, but not physically, symmetrical security element. The use and coloring of the protective layer 13 is also optional in this case. The adhesive layers 16 described in Examples 13 can also be used on the outer surfaces of the laminate.

In the modification of the security element shown in Fig. 11, the selectively metallized areas 12 are made of aluminum and the support layer is dyed with a yellow dye. The continuous metal layer is also aluminum. When the paper containing such a security element is viewed from above through the windows of the security paper, the patterns appear in bright silver and gold. In this variation, two security elements may be placed on the backside to provide a symmetrical security element that does not require precise placement on the paper of the present invention.

Various shaped security elements can be used in the papers of this invention. The safety element can consist of e.g. a polyester substrate having a continuous aluminum layer on one side and a selectively metallized surface provided by pressing with a metal-containing ink such as gold-colored ink to provide a security wire with a contrasting pattern of gold-colored areas and silver-colored areas. The polyester substrate may optionally contain a dye so that the pattern has gold-colored areas as well as areas formed by another reflective color. In addition, the areas printed with the metal-containing ink can be printed directly on the aluminum layer supported by the polyester film.

Another security element according to the present invention uses selectively metallized aluminum areas on top of the clear polyester support layer, which are obtained by demetallizing the continuous aluminum layer. This demetallized element is then laminated to an adhesive-dyed polyester layer with a continuous layer of matt aluminum on one side so that the selectively metallized areas are between the two polyester layers. When a security element such as that described is viewed through the windows of the security paper from the side of the outer clear polyester layer, the pattern appears as aluminum areas and colored reflective areas. Because the selectively metallized aluminum areas are protected by an outer polyester layer, better mechanical and / or chemical resistance is obtained.

A security element according to the present invention has three or more areas, each of which has its own reflective color. This is illustrated in Figure 13. Layer 11A contains clear polyester that is selectively demetallized to provide matte aluminum regions 12 on one surface. A blue transparent layer is attached to the outer surface of the areas 12. The second clear polyester layer 11B is also demetallized to provide matte aluminum regions 19.

The two reinforced polyester layers are laminated as shown with a clear adhesive 18. A continuous layer 14 of another metal, e.g. copper, is then vacuum-applied to the lower surface of the laminate.

The areas 12 and 19 are arranged in an obstacle-shaped pattern over the entire width of the security element so that the areas 19 are not below the areas 12.

When the security element is considered to split the reflected light of the security paper window areas in the direction of the arrow 12 shows the areas of the metal in blue, the regions 19 in silver and remain between the areas to the layer 14, the copper color.

In practice, it is advisable to shape the security elements of the present invention by making webs of material containing different layers and modifying a pattern across the width of the web which, after cutting the web into strips or strips, provides a security element that can be used in the paper of the present invention.

In addition, it is to be understood that the present invention includes novel safety wires as described above.

The terms fluorescence and

II fluorescent means phosphorescent and phosphorescent. The provision of fluorescence is also not limited to ultraviolet radiation, but also includes infrared or other suitable radiation.