DE102012012218A1 - Security paper, useful for producing checks, tax bandroles, tickets and admission ticket and as base paper for stamps, comprises particulate security elements, which are marked with DNA-single strands of defined sequence - Google Patents

Abstract

Security paper comprises particulate security elements, which are marked with DNA-single strands of defined sequence. Independent claims are included for: (1) the particulate security elements for the production of security paper, where the particulate security elements are marked with DNA-single strands of defined sequence; and (2) producing the security paper, comprising adding a pulp prior to introduction into a paper machine of the particulate security elements, which are marked with the DNA single strands of defined sequence.

Description

The present invention relates to a security paper which is provided with security features, by means of which the authenticity can be verified and a method for its production.

It has long been known to provide paper and documents and valuables made thereof with security features to determine the authenticity and not only to recognize counterfeiting, but also to prevent. Examples of security features are watermarks, mottling fibers, so-called starlights, planchettes, threads, and chemical reaction systems.

Watermarks are usually pressed into the wet paper web in the papermaking process by means of a dandy cutter, so that the paper is thinner at this point and the watermark is recognizable in the backlight as a bright mark.

Melierfasern usually consist of short fibers that are colored or provided with a fluorescent coating. Fluorescent mottled fibers are invisible under normal illumination, but under UV illumination they appear clearly despite their small size due to their bright fluorescence. Planchettes are small platelets in round or polygonal shape, which can be inserted into the paper over the entire surface or within a defined strip.

Security papers provided with these security features are used, for example, for making checks, tax stamp rolls, as a base paper for stamps, for tickets and tickets. For example, the current euro banknotes contain uniformly embedded mottled fibers with the fluorescent colors red, blue and green.

The security features mentioned above are well-known features for a long time, so that the security against counterfeiting no longer seems completely guaranteed. This is especially true with regard to the rapidly evolving methods of reproduction by means of, for example, modern color printers, scanners, etc.

Chemical reaction systems work according to the so-called "key lock principle". This is based on a chemical reaction, usually the formation of a dye, for which two components are required. One component is in the paper, the second, for example, in a test pen or stamp. If the label is brought into contact with the first component with the second component, a reaction is carried out, which is observable optically as a color. However, these reactions and the components required for this are largely known and can therefore be adjusted relatively easily.

A recent development for the security marking of valuables according to the "key lock principle" is based on the complementary single strands of a usually artificially generated DNA. Here, the object is labeled with a first defined nucleotide sequence. To identify the label, the first nucleotide sequence is contacted with a complementary second nucleotide sequence. The first and second nucleotide sequences combine to form a double strand (hybridization), triggering a reaction that is detectable or visible. Typically, the reaction is a fluorescence reaction. For a suburb proof a hand scanner can be used which works at a defined wavelength.

The second nucleotide sequence (hereinafter referred to as "detection DNA") resides in a solution in a dosing device, for example a pen, which, if necessary, scans the label with the first nucleotide sequence (referred to hereinafter as "tag DNA") to the two Contact individual strands and trigger the reaction.

For marking articles, it is known to add the marking DNA to an ink (for example DE 10 2005 012 567 A1 ). At a predetermined location of the object to be marked then an optionally colored mark with the printer ink, which is mixed with labeling DNA, printed. This method is already used today for the marking of bills, high-quality branded products and for the labeling of medicines.

Forgery possibilities arise only if both the ink used and the corresponding test pen concerned with the complementary DNA strand or the marker sequence can be isolated and analyzed. To increase safety, it is therefore known to hide the label DNA in the ink under other, irrelevant DNA substrings. For imitators, it is then no longer possible to recognize which of the multiplicity of DNA partial strands in the ink is the labeling DNA. An isolation and replication of the labeling DNA is thus almost impossible, or at least significantly more difficult.

However, this method is limited to finished articles or already printed paper. In addition, the locations provided with marker DNA must be identified on the item or document so that the person responsible for the examination can identify the items to be examined. If these locations have been knowingly or accidentally removed, authenticity testing is no longer possible. This concerns, for example, tickets or tickets, which are canceled by tearing off certain sections. If the tags are removed or unrecognizable with the cancellation, it is no longer possible to determine the authenticity in a possibly required second check.

It would therefore be desirable to already mark the unprinted paper web by means of DNA, wherein the security feature should be distributed substantially uniformly over the entire paper surface. However, coating the total area of a paper web with DNA is uneconomical due to the high cost of the DNA. If the DNA is added to the aqueous pulp in the course of papermaking, there is a risk that the tag DNA will be washed out with the water. Not only does this result in the loss of expensive label DNA, it can also lead to undesirable contamination of subsequently produced paper webs.

There was therefore a desire for a method by which not yet printed paper - prior to its use for the production of articles thereof, such as bills, tickets, etc. - can be treated with marker DNA as a safety feature without the above-mentioned disadvantages and a security paper containing tagging DNA as a safety feature.

According to the invention, this problem is solved by marking particulate security elements which are added to the paper pulp in papermaking with a first single strand of DNA as marking DNA and adding these DNA-labeled security elements to the paper pulp.

Thus, a targeted doping of the paper with DNA is possible Furthermore, the doped areas are clearly recognizable as such by means of the security elements, so that they can be clearly identified for the later implementation of the authenticity test.

As particulate security elements, mottled fibers or planchettes can be used. These particulate security elements may be colored and / or fluorescent. Due to their color or fluorescence they can be easily localized on the paper. Different colored security elements can be used, wherein, for example, only the security elements of a particular color can be labeled with DNA.

According to one embodiment, the paper web can be made of several layers, and the DNA-labeled security elements can be added either only to the upper or lower layer.

The security element is labeled with a first nucleotide sequence of defined composition as marker DNA. The labeled security elements are added in a desired amount to the paper pulp for the manufacture of security paper marked therewith. The location of the mark can easily be identified on the finished security paper due to the clearly identifiable security elements. For the detection of the marking and checking the authenticity, the complementary nucleotide sequence (detection DNA) dissolved in a test solution is applied to the relevant area of the paper and the first nucleotide sequence thus brought into contact with the second nucleotide sequence. As a result of the hybridization, for example, the optical properties of the second nucleotide sequence change, the change being observable. For example, a fluorescence signal can be triggered, which can be detected by means of a suitable device. For example, a hand-held scanner can be used which operates at a corresponding wavelength, so that on-site detection is possible. If fluorescent security elements are used at the same time, the excitation wavelengths of the fluorescence signals should be significantly different.

As fluorescence-triggering second nucleotide sequences, it is possible, for example, to use so-called molecular beacons which are functionalized with a fluorophore. Molecular beacons and their use as hybridization probes are in EP 0 745 690 A2 described. A method of detecting DNA tags by means of such hybridization probes is out of the question WO 01/51652 A2 known.

For the labeling and detection, synthetic or naturally occurring nucleic acids of known sequence can be used. For example, synthetic nucleotide sequences can be used as they are manufactured and sold by the company SecuTech Europe GmbH.

The number of nucleotides of the DNA single strands is not particularly critical per se. A high number offers the advantage of correspondingly higher combination possibilities. The disadvantage here, however, is that with the number also increases the error rate and strands are obtained with incorrect combination.

A suitable number of nucleotides may be between 5 and 100, in particular 10 to 50 and particularly preferably 10 to 30.

In addition to the tag DNA, other irrelevant nucleotide sequences can be used to label the tag DNA so as to prevent isolation of the tag DNA by potential imitators.

For the present invention, security elements are used, which are stored in the paper pulp. These may be particulate security elements known as "mottled fibers" or "planchettes". Conventional mottled fibers have a length of up to 20 mm, preferably from 3 to 12 mm and more preferably from 4 to 6 mm. Planchettes are platelets, which may have any circumferential shape and have a size dimension of up to 5 mm, preferably 0.5 to 1.5 mm.

It is understood that for the present invention, other particulate security elements can be used, which can be stored in the paper pulp in the paper pulp.

The security elements used according to the invention can be made of a wide variety of materials. Synthetic, natural or semi-synthetic materials can be used. Examples of synthetic materials include plastics such as polyethylene, polypropylene, aramid, polyamide, polyacrylonitrile, polyesters such as polyethylene terephthalate, etc. Examples of natural materials are cellulose or vegetable fibers such as cotton etc. Examples of semi-synthetic materials are cellulose derivatives such as cellulose acetate or cellulose based materials such as viscose ,

Preferably, readily available materials are used which are well anchored in paper, such as polyamide, cellulose or viscose.

For labeling with the tag DNA, the security elements may be coated with tag DNA or coated with tag DNA. The tag DNA may be covalently coupled to the security elements via the surface of the security elements or to a coating thereof via reactive groups. The coupling can take place via reactive groups which are already present in the material of the security elements and / or marker DNA. The security elements, their coating and / or labeling DNA can also be functionalized by introducing reactive groups if required. In principle, the coupling can take place via reactive groups, as are known from the immobilization of DNA single strands on carrier surfaces. Commonly used groups are amino, epoxy and carboxyl groups.

The attachment of the tag DNA to the security elements should be as water-insoluble as possible in order to prevent or at least reduce as much as possible during the papermaking process.

Hereinafter, the present invention will be explained in more detail by way of example with colored mottled fibers as security elements. Commercially available colored mottling fibers can be used for this purpose.

The use of colored particulate security elements, such as colored mottled fibers or planchettes, has the advantage that they can be seen on the paper with the naked eye without further aids.

For papermaking, the pulp base, such as paper fibers, is first dissolved in water and ground. Subsequently, the other paper components, such as fillers, starch, glue, optical brightener, dyes, etc. and various process aids, such as retention aids, dehydrating agents, etc., which support the formation of the paper on the paper machine, dosed as needed. The resulting aqueous mixture, the so-called pulp, typically has a solids content of up to 1% by mass. This pulp is fed to the paper machine and first applied to a sieve for dewatering. For further dewatering, the paper web is pressed and then dried. The paper surface is then typically coated, usually with a mixture of starch and hydrophobing agent, for example to be able to adjust the printability. There is a post-drying and smoothing, for example, with the help of press rolls and finally winding.

The security elements are added to the pulp before being loaded onto the paper machine. The amount added depends on the desired number of security elements per dm ² . Typical values are up to 400 per dm ² , in particular 10 to 30 per dm ² .

Since the colored mottled fibers are readily discernible to the naked eye on the paper web, it is easy to identify the areas to be treated with the complementary nucleotide sequence in order to verify the authenticity.

For the attachment of the tag DNA, the mottled fibers may be coated with a tag-DNA containing material. According to a preferred embodiment, the labeling takes place via a chemical coupling of the labeling DNA to the surface of the mottling fibers. For the formation of the covalent bond, the label DNA and / or the surface of the mottled fibers may be chemically functionalized. For this functional groups can be used, as they are known from the immobilization of nucleotide sequences on solid supports.

Examples of suitable reactive groups are amino, epoxy and carboxyl groups. The tag DNA can be functionalized with an amino group. For example, a 5'-end amino-terminated label DNA can be used. For chemical bonding by condensation, the mottled fibers can be coated, for example, with epoxy silane.

The reaction is shown schematically below:

The amount of label DNA that is coupled to the mottled fibers is not particularly limited, but is typically selected to be sufficient for unambiguous identification but, on the other hand, does not make the product unnecessarily expensive.

The present invention makes it possible to provide a security paper with DNA tag, without the need for a full-scale application of label DNA, but on the other hand, the sites that have label DNA are clearly identifiable.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102005012567 A1 [0010]
• EP 0745690 A2 [0020]
• WO 01/51652 A2 [0020]

Claims (11)

Security paper containing particulate security elements labeled with DNA single strands of defined sequence. The security paper of claim 1, wherein the particulate security elements are mottled fibers and / or planchettes. Security paper according to claim 1 or 2, wherein the particulate security elements are colored and / or fluorescent. A security paper according to any one of the preceding claims wherein the particulate security elements are provided with a coating comprising the single DNA strands. A security paper according to any one of the preceding claims, wherein the single strands of DNA are covalently bound to the particulate security elements. Particulate security elements for the production of security paper, wherein the particulate security elements are labeled with DNA single strands of defined sequence. The particulate security element of claim 6, wherein the particulate security elements are mottled fibers and / or planchettes. Particulate security element according to claim 6 or 7, wherein the particulate security elements are colored and / or fluorescent. A process for the production of security paper, wherein the pulp before being introduced into the paper machine, particulate security elements are added, which are labeled with DNA single strands of defined sequence. A method of making security paper according to claim 9, wherein the particulate security elements are mottled fibers and / or planchettes. The method of claim 9 or 10, wherein the particulate security elements are colored and / or fluorescent.