WO2000000697A1

WO2000000697A1 - Antifalsification paper

Info

Publication number: WO2000000697A1
Application number: PCT/EP1999/004471
Authority: WO
Inventors: Reinhard Plaschka; Theo Burchard
Original assignee: Giesecke & Devrient Gmbh
Priority date: 1998-06-29
Filing date: 1999-06-28
Publication date: 2000-01-06
Also published as: EP1099024B1; EP1365069A2; PT1099024E; CN1307658A; ID27465A; EP1099024A1; DK1099024T3; DE59908592D1; CN1238603C; DE19829004A1; ES2216529T3; EP1365069A3; AU4779099A; ATE259916T1; KR20010071507A

Abstract

The invention relates to an antifalsification paper for producing valuable documents such as banknotes, passports, identity cards or similar. At least part of the inventive paper is provided with a coating which guarantees a longer period of circulation. Said coating is provided on at least one surface of the antifalsification paper and consists of a composition containing only one binder and no fillers.

Description

Security paper

The invention relates to a security paper for the production of documents of value, such as banknotes, passports, identity cards or the like, which is provided with a coating which ensures increased fitness for circulation, and a method for the production of such a security paper.

Banknotes are usually made from so-called security papers, which consist of cotton fibers and have special security features, such as a security thread at least partially incorporated into the paper and a watermark. The duration of circulation of a banknote depends on the stress. Certain denominations are preferred in trade and therefore have a shorter orbital period due to the greater burden of environmental influences. The main reason for the restricted circulation period of banknotes is early soiling. Since banknote paper is very porous, it has a large surface or a high surface roughness. Even if the resulting projections and cavities are of a magnitude that can no longer be resolved by the human eye, they offer ideal conditions for dirt deposits compared to a smooth surface.

AU-PS 488,652 has therefore already suggested that banknotes be made entirely from a plastic substrate. In this case, however, the usual and proven security elements, such as portrait

Watermarks and window security thread are dispensed with, as well as the special properties such as the sound and grip of the banknote paper. The printing in rotogravure printing that is common in the banknote sector, which serves as an additional tactile authenticity indicator due to the relief created by the application of paint, only leads to a flat, barely noticeable relief on plastic substrates. The object of the invention is therefore to produce a security paper which is dirt-repellent and therefore has a long circulation period and which remains unchanged in its other typical properties, such as printability, sound, color, etc.

The solution to this problem results from the independent claim. Further training is the subject of subclaims.

According to the invention, the security paper is provided at least on one of its surfaces with a coating which consists of a composition which contains only a binder and no fillers. A binder in the sense of the invention is formed by all substances which form films or structures which are insoluble in common solvents. It is essential that, unlike conventional coating materials, the binder does not contain any fillers, i.e. Contains pigments, such as titanium dioxide, in high concentrations. This composition wets the fibers in the surface area of the paper and forms a closed surface film over the fiber. This minimizes dirt access to the fiber.

The composition is applied in a layer thickness so that on the one hand a sufficiently smooth surface is created and there are as few possibilities for dirt accumulation as possible. On the other hand, the layer thickness is so small that the other properties of the paper, such as its grip and printability, are not impaired. The basis weight of the coating here is preferably approximately 1 to 6 g / m ² , in particular 2 to 3 g / m ² .

At around the low coating thicknesses, the transmission properties of the paper remain unchanged, so that even current portrait watermark in the security paper is not impaired. The coating also has the advantage that the usual sizing of the paper can be dispensed with. There are also no conditions attached to the type of security paper, so that customary security papers made from annual plants, in particular cotton fibers, can be used, but also security papers that at least partially consist of plastic fibers, preferably polyamide fibers.

Polyamide coatings, acrylates or binder systems which contain a high percentage of acrylates are preferably used as binders. If the binder system has several polymer components, these can be present as a mixture or as copolymers. In principle, other binder systems are also conceivable. Compositions which can be crosslinked chemically or physically have proven particularly useful.

Acrylate systems in particular have a number of advantages over other, for example polyurethane-based, binder systems. They have better printing properties and generally contain fewer solvents, so that there is less environmental pollution during processing. The acrylate coatings are also characterized by a higher surface hardness, so that the dirt-repellent effect is improved. Finally, the acrylate systems have the advantage that they are considerably cheaper than other binder systems and can be mixed well with other polymers.

The binder composition is applied to the paper after it has been produced, or by a knife. This can be done directly after the paper production in the paper machine or in a separate work step, for example directly before printing on the security paper. If necessary, the smoothness of the surface can then be increased by means of an appropriate calendering. The paper coated according to the invention offers an ideal printing surface for high printing resolution and very good printing ink adhesion in physical and / or chemical attack attempts.

The security paper according to the invention is then printed in accordance with the security to be produced and possibly further processed. An imprint or embossing, especially if it was created using the gravure printing process, leads to a new rough surface and therefore favors dirt deposits. In order to exclude this as well, it is proposed according to the invention to print with a further binder layer, e.g. to cover a layer of lacquer. The composition of the lacquer layer is preferably matched to the substrate layer according to the invention in order to enable a good bond between the two layers. The network can possibly be improved by an additional networking step. This can be done by exposure to heat or radiation (e.g. with UV radiation). Since the printing can be done using any printing method, e.g. can be produced in steel gravure printing or with a laser printer, it may be necessary to adapt the binder composition according to the invention in accordance with the printing process used, in order to ensure, in addition to the low contamination, an improved adhesion of the printing inks to the substrate.

Another advantage of the invention can be seen in the fact that a further pretreatment of the security paper according to the invention can be dispensed with if optically variable security elements are to be provided on the paper. Optically variable elements or printing inks that Due to light diffraction or interference, a play of colors depending on the viewing angle requires the smoothest possible surface for this effect to be visible. Security elements of this type are, for example, holograms, kinegrams or other diffraction structures, but also printing inks which contain interference layer or liquid crystal pigments or other effect pigments, such as shiny metallic effect color pigments.

In special cases, however, it can still make sense to provide a further background layer in the area of this element. Liquid crystal pigments and interference layer pigments, which consist only of mica platelets coated with titanium dioxide, are translucent, so that the color effect is influenced not only by the smoothness but also by the color of the substrate. A black background absorbs the light transmitted by the pigments and in this way increases the brilliance of the colors reflected by the pigments. The same applies to security elements that are made up of several thin layers and also show a play of colors based on interference effects. For these and similar elements, it may therefore be necessary to provide the security paper with a further background layer in the area of the security element to be applied.

Alternatively, it can also be expedient to underlay the security element with a machine or visually verifiable authenticity feature, as is known, for example, from WO 97/35732.

The coating according to the invention also has an advantageous effect on other security elements. Embossed structures, for example, are becoming more distinctive because the embossing is more pronounced due to the smoother surface. step forward. The embossing is also more durable because it is not only the paper fibers that are embossed.

According to a preferred embodiment, the coating composition additionally contains in a low concentration at least one substance with a visually and / or machine-detectable physical property. The substance can, for example, have magnetic, electrically conductive, light diffractive, light polarizing or light interfering properties and can be uniformly distributed over the entire surface or applied in the form of patterns. In a first step, a composition is preferably printed in the form of a specific pattern, which in small amounts in the manner of a doping (<1% by weight) contains at least one substance with at least one visually and / or machine-detectable physical property. Only in a second step is the register of the first part of the remaining part of the surface of the paper provided with the same composition, which, however, does not contain the detectable additive.

These additives can be, for example, luminescent substances that can be excited with UV light and emit in the visual spectral range. In the case of a machine check, however, luminescent substances emitting in the invisible spectral range, preferably in the IR spectral range, can also be used. Photochromic or thermochromic additives are also conceivable.

Instead of physically detectable substances, however, chemically reacting additives can also be used. For example, a component of a color reaction system can be added to the binder composition and applied to the paper. If you bring it to a late When the second component of the color reaction system is reached, a colored area, pattern, lettering or the like becomes visible on the security paper. This can serve as an authenticity feature or also as a cancellation indicator for a check, ticket or the like.

By using several additives and / or varying the concentration of one or more additives, any coding, for example in the form of a bar code, can be generated very easily on the security paper. This coding can, for example, represent an independent additional security feature or serve as a comparison feature for other data already provided on the security paper. In this way, visually visible information, such as the denomination, the name of a person represented in the portrait or the like, can be encoded on the banknote and stored on the paper in the form of the coding according to the invention invisible to the eye. During a machine check, the coding is read, decrypted and checked for identity using the corresponding, visually visible information.

According to the principle of the invention, several different codes can of course also be generated. For example, the binder compositions containing the respective additive are applied to the paper in the form of the desired codes at the same time or in succession. As already explained, the remaining part of the paper surface is printed or coated with the additive-free binder composition. Alternatively, the different codes can also be arranged on different surfaces of the security paper. A coating on both sides with the same additive is of course also possible. According to a further embodiment, the coating according to the invention can also have cutouts. These recesses can have any shape, for example a strip shape. Before or after the application of the coating according to the invention, they are provided with an imprint which has certain effect colors. These effect colors can be interference layer pigments, liquid crystal pigments or other gloss pigments. This imprint can cover the recesses over the entire surface or only partially.

The security paper according to the invention can also be used advantageously, for example, for the production of identity cards and passports. Since it has increased tear resistance and dirt resistance, the usual lamination with plastic films can be dispensed with. If lamination is nevertheless carried out, the coating according to the invention ensures a firm, inseparable bond between paper and cover layer.

Some examples of the composition according to the invention are explained below:

example 1

A banknote paper made of 100% cotton with a filler content of 3.0% is used for the coating test. The paper is adjusted to a wet strength of 50% relative to the dry strength using commercially available melamine resin (e.g. Madurit MW167).

The following recipe is used as the coating: Acronal 320D (BASF) 400 ml

- aqueous dispersion of an acrylic resin -

softened water 600 ml.

The mixture is prepared by stirring and applied to the surface of the paper. For this a rotating pair of rollers is used, the lower side of which is immersed in a bowl with the diluted Acronal dispersion. The excess of the suspension is pressed out through the nip. The paper is then dried using a commercially available photo dryer.

The treatment gives the paper the following properties:

Example 2

In the same way as set out in Example 1, a paper is coated with the following recipe:

Neocryl-AC 72 (Zeneca) 900 ml

- aqueous dispersion of an acrylate

Water 80 ml Curing agent CX 100 (Zeneca) 20 ml

Example 3

The paper can also be coated with the following binder composition:

Primal 1-545 (Rohm & Haas) 900 ml

- aqueous dispersion of an acrylate -

Water 80 ml

Zirconium carbonate (Auer Remy) 20 ml.

Example 4

The binder system according to the invention can also consist of a mixture of several polymers. The following recipe is given as an example:

Glascol LS 26 (Ciba) 700 ml

- aqueous dispersion of an acrylic-styrene copolymer -

Polyurethane U 400 N (Alberdink Boley) 200 ml

Water 100 ml. Further advantages and embodiments are explained in more detail with reference to the figures. It is pointed out that the figures only schematically represent the layer structure of the security paper according to the invention. It shows

1 is a security paper according to the invention in supervision,

Fig. 2 shows a section along A - B through the Invention

1,

Fig. 3 shows a further embodiment of an inventive

Security paper under supervision,

4 cross section along A - B through the security paper according to the invention according to FIG. 3.

1 shows a section of a security paper web 1 according to the invention, as is used, for example, for the production of banknotes. Such security paper is usually made from cotton fibers or other fibers from annual plants. For some applications, however, it can also make sense to replace some of these natural fibers with plastic fibers, in particular polyamide fibers. Pure plastic fiber papers are also conceivable. During the production of the paper web 1, individual security elements are already embedded in the paper, such as a portrait watermark or the security thread 2 shown in FIG. 1. This security thread 2 is quasi woven into the paper, so that it is directly attached to the areas 3 the surface of the paper treads while it is completely embedded in the paper mass in the areas shown in broken lines. This thread 2 can be any security features, such as an electrically conductive, metallic layer, a hologram or the like.

FIG. 2 shows a section through the security paper 1 according to the invention along the dash-dotted line AB in FIG. 1. The security paper 1 according to the invention consists of the base paper 4, as it usually leaves the paper machine, and the binder coating 5 according to the invention, which is shown in FIG Embodiment was doctored or printed over the entire surface of a surface of the security paper 1. Alternatively, however, the coating 5 can also be applied to the security paper 1 on both sides.

3 and 4 show a further embodiment of the security paper 1 according to the invention. FIG. 4 shows a section through this security paper 1 according to the invention along the line A - B drawn in broken lines in FIG. 3.

As shown in FIG. 4, the security paper 1 also consists of a conventional paper web 4 which, according to the invention, is provided with a pure binder composition without fillers. However, the binder layer is composed of different areas 6, 9. In areas 6, the binder composition is doped with an additive that can be checked visually and / or by machine, while the remaining areas 9 of the binder vibrating composition contain no additive. As can be seen from FIG. 3, the area 6 represented by means of the doped binder composition forms visually readable information. The areas 7 likewise represented with the doped agent composition form a code 8 in the form of a bar code. The additive can be, for example, a luminescent substance which is transparent under normal lighting and which emits in the visual spectral range when irradiated with UV light and thus shows an intense color tone. In this case, the information 6, 8, as shown in FIG. 3, is only visible under UV illumination.

However, it is also possible to provide several additives which can be detected individually. Additional coding can be generated using the mixing ratio of the additives. It is also conceivable to generate the information 6, 8 with different additives. Thus, as already explained, the information 6 can be generated with the aid of a luminescent substance which emits in the visual spectral range, while the barcode 8 with the aid of a substance which can only be detected by machine, e.g. of a luminescent substance emitting in the IR spectral range. The characters 6 that are visually visible under UV illumination can represent, for example, an image, pattern or legible information. The machine-readable code 8, on the other hand, could represent certain information indicative of the individual value document, possibly in encrypted form. This information could be properties inherent in the paper material, such as the transmission properties, thickness distribution, etc., or other information that is essential for the respective value document, such as denomination or the like.

Claims

Patent claims

1. Security paper for the production of documents of value, such as banknotes, passports, identity cards or the like, which is at least partially provided with a coating which ensures increased fitness for circulation, characterized in that the coating is provided on at least one of the surfaces of the security paper, and that the coating consists of a composition that contains only a binder and no fillers.

2. Security paper according to claim 1, characterized in that the composition is present in a coating weight of 1 to 6 g / m ² , preferably 2 to 3 g / m ² , on the security paper.

3. Security paper according to claim 1 or 2, characterized in that the composition contains, as a binder, acrylates or a mixture of polymers or copolymers with a high proportion of acrylate.

4. Security paper according to at least one of claims 1 to 3, characterized in that the composition contains in low concentration at least one substance with a visually and / or machine-detectable property.

5. Security paper according to claim 4, characterized in that the substance has luminescent, magnetic, electrically conductive, light diffractive, light interfering or light polarizing properties.

6. Security paper according to claim 4 or 5, characterized in that the substance or substances is only partially, preferably provided in the form of a pattern in the coating.

7. Security paper according to at least one of claims 1 to 6, characterized in that the security paper consists of fibers from annual plants, in particular cotton fibers.

8. Security paper according to at least one of claims 1 to 7, characterized in that the security paper consists at least partially of plastic fibers, preferably polyamide fibers.

9. Security paper according to at least one of claims 1 to 8, characterized in that the security paper is an ungeleited paper.

10. Security paper according to at least one of claims 1 to 9, characterized in that the coating is applied to the security paper only in certain areas, and that the coating-free areas are printed with a printing ink which contains effect pigments.

11. document of value, such as a bank note, check, identity card or the like, characterized in that the document of value comprises a security paper according to at least one of claims 1 to 10.

12. A document of value according to claim 11, characterized in that the document of value has an imprint over the coating, which in turn is covered by a coating, for example a layer of lacquer.

13. A method for producing a security paper according to at least one of claims 1 to 10, characterized in that a paper layer is produced in a paper machine and then a coating is at least partially applied to at least one of the surfaces of the paper, the coating consisting of a Composition consists of only a binder and no fillers.

14. The method according to claim 13, characterized in that the paper is sized before the application of the coating.

15. The method according to claim 13 or 14, characterized in that the coating is printed.

16. The method according to at least one of claims 13 to 15, characterized in that the coating is applied in several steps.

17. The method according to claim 16, characterized in that in a first step, a composition is applied in the form of a pattern, which in small quantities contains at least one substance with at least one visually and / or machine-detectable physical property, and that in a second step the remaining part of the surface of the paper is provided with the same composition without the detectable substance in register with the pattern.