Catalytic antimicrobial cleaning of a document of value

Abstract

The present invention relates to the catalytic antimicrobial cleaning of a document of value, such as a banknote or an identity document, for example. Described is a document of value comprising a substrate having optionally two layers applied oppositely thereon, and optionally at least one further layer, where the substrate and / or, if present, at least one of the two oppositely applied layers, and / or, if present, at least one of the at least one further layer, contains bimetal silver-ruthenium particles over the full area. Further described are a method for catalytic antimicrobial cleaning of a document of value, comprising the step of introducing bimetal silver-ruthenium particles into at least one layer of a document of value, over the full area, and the use of bimetal silver-ruthenium particles for the catalytic antimicrobial cleaning of a document of value, where the bimetal silver-ruthenium particles are contained in at least one layer of the document of value, over the full area.

Description

[0001] CATALYTIC ANTIMICROBIAL CLEANING OF A VALUABLE DOCUMENT

[0002] Technical area

[0003] The present invention relates to the catalytic antimicrobial cleaning of a valuable document, such as a banknote or an identification document. Thus, the present invention relates to a valuable document comprising a substrate with optionally two opposing layers applied thereto, and optionally at least one further layer, wherein the substrate and / or, if present, at least one of the two opposing layers, and / or, if present, at least one of the at least one further layer, contains silver-ruthenium bimetallic particles over its entire surface.Furthermore, the present invention relates to a method for the catalytic antimicrobial cleaning of a value document, comprising the step of introducing silver-ruthenium bimetallic particles into at least one layer of a value document over the entire surface, as well as the use of silver-ruthenium bimetallic particles for the catalytic antimicrobial cleaning of a value document, wherein the silver-ruthenium bimetallic particles are contained in at least one layer of the value document over the entire surface.

[0004] Technical background

[0005] Valuable documents, such as banknotes and identification documents, especially banknotes, come into contact with a wide variety of environments within a short period of time due to their intended use. In particular, valuable documents frequently come into contact with the human skin of different people, for example, during payment transactions with banknotes or when verifying identification documents. Many people are concerned that this could pose a risk that microorganisms of all kinds, including potential pathogens such as bacteria and viruses, as well as fungi, could be transmitted from one person to another via valuable documents. This concern is understandable but unjustified. It has been shown that microorganisms on banknotes, regardless of whether they are made of plant fibers, plastic, or a combination thereof (hybrid banknotes), and on other objects made of or containing paper, remain pathogenic for only a few hours.Furthermore, most of the microorganisms found on banknotes and other frequently handled objects are not capable of harming the health of an averagely healthy user. Nevertheless, it cannot be ruled out that, due to an unfortunate chain of circumstances, the transmission of microorganisms leading to illness could occur.

[0006] In order to achieve a certain level of antimicrobial cleaning of circulating valuable documents, especially banknotes, it has been proposed that such valuable documents be subjected to an additional antimicrobial cleaning process, for example, during a routine authentication check, such as banknotes before they are used to deposit cash into ATMs in a bank. Such an antimicrobial cleaning step is usually carried out by irradiating the banknotes with high-energy radiation, such as UV radiation. However, this approach has several disadvantages. Firstly, such cleaning in a central institution, such as a bank, requires that the banknote actually returns to that institution.However, statistically, this can take a very long time for many banknotes in circulation, making this approach unsuitable for ensuring regular antimicrobial cleaning of all banknotes, let alone within short intervals. Furthermore, such antimicrobial cleaning requires the purchase of suitable equipment, which entails undesirable costs. Last but not least, antimicrobial cleaning with irradiation is quite time-consuming, as the banknotes must be irradiated individually for a sufficiently long time to achieve the desired antimicrobial cleaning.

[0007] Identity documents are typically covered with an outer plastic coating and, unlike banknotes, are used by a single person, who occasionally passes them on to other people, but receives them back after use and otherwise keeps them safe. Such identity documents could, in principle, be cleaned by the user themselves using standard household antimicrobial cleaners. However, this is done only to a very limited extent in practice.

[0008] A novel approach for the antimicrobial cleaning of valuable documents, in particular banknotes, using UV radiation and photosensitizers to generate singlet oxygen, which overcomes some of the aforementioned disadvantages, is described, for example, in WO 2021 / 197663 A1. Photosensitizers such as those described in WO 2017 / 032892 A can be used. In this approach, a photosensitizer is incorporated into a valuable document, which generates singlet oxygen upon irradiation with UV radiation. The singlet oxygen can then diffuse through the various layers of the valuable document and, for example, act as a highly reactive species on the valuable document's surface, killing microorganisms and thus contributing to antimicrobial cleaning.The system is designed in such a way that the UV radiation from UV lamps commonly used at cash registers to verify banknotes is sufficient to stimulate the photosensitizer. This enables significantly more regular antimicrobial cleaning than the centralized cleaning approach described above. However, even this approach cannot ensure regular antimicrobial cleaning of all valuable documents in circulation because, firstly, not all cash registers are equipped with UV devices. Secondly, the verification time is usually very short, allowing for the verification of only one or two security features, meaning that the valuable document cannot be exposed to UV radiation long enough for the photosensitizer to generate a sufficient amount of singlet oxygen.Last but not least, there is a trend that only higher-denomination banknotes are subjected to UV light inspection at cash registers (for example, in the Eurozone, banknotes of €50 and above are regularly subjected to UV light inspection). However, lower-denomination banknotes are particularly exposed to a high risk of microbial, particularly fungal, contamination, as they generally circulate much more frequently than higher-denomination banknotes. In practice, however, such lower-denomination banknotes are not checked for authenticity with UV light sufficiently frequently, if at all.

[0009] The present invention is therefore based on the object of providing value documents with improved antimicrobial, for example improved antifungal, antibacterial, and / or antiviral, and in particular improved antifungal cleaning properties compared to the prior art. For example, it would be desirable if antimicrobial cleaning of the value document could be carried out decentrally, ideally continuously. Furthermore, it would be desirable if the antimicrobial cleaning of the value document did not require any special additional conditions to which a banknote is not exposed or only to a very small extent in a normal environment, such as UV radiation. The present invention, as described herein and defined in the independent claims, solves this object. The dependent claims represent preferred embodiments.

[0010] Summary

[0011] According to a first aspect, the present invention relates to a value document comprising a substrate with optionally two layers applied thereon opposite one another, and optionally at least one further layer, wherein the substrate and / or, if present, at least one of the two oppositely applied layers, and / or, if present, at least one of the at least one further layer contains silver-ruthenium bimetallic particles over its entire surface.

[0012] The present invention further relates, according to a second aspect, to methods for the catalytic antimicrobial cleaning of a value document, comprising the step of introducing silver-ruthenium bimetallic particles into at least one layer of a value document, preferably a banknote or an identification document, over the entire surface.

[0013] The present invention further relates, according to a third aspect, to the use of silver-ruthenium bimetallic particles for the catalytic antimicrobial cleaning of a value document, preferably a banknote or an identity document, wherein the silver-ruthenium bimetallic particles are contained over the entire surface of at least one layer of the value document.

[0014] Detailed description of the invention

[0015] The present invention is based on the discovery that silver-ruthenium bimetallic particles contained in a substrate and / or in at least one further layer of a valuable document are capable of continuously cleaning the valuable document in an antimicrobial and, in particular, antifungal manner. Antimicrobial cleaning does not require UV radiation; instead, it merely requires the presence of oxygen, for example, from the ambient air, since the silver-ruthenium bimetallic particles catalytically convert oxygen into hydrogen peroxide in the presence of two protons. This occurs through a complex mechanism by which the electrons generated by the catalytic oxidation of organic matter with silver are transferred to oxygen via a redox cascade comprising ruthenium, forming hydrogen peroxide. This process is supported by ambient humidity.The inherently unstable hydrogen peroxide decomposes in a further step into two hydroxy radicals, which can diffuse through the layers of the valuable document. As highly reactive species, these radicals can kill microorganisms such as bacteria, viruses, and / or fungi upon contact, thus contributing to an antimicrobial, preferably antifungal, cleaning of the valuable document. The reaction is particularly rapid on the surface of the valuable document because, on the one hand, it is in direct contact with atmospheric oxygen and thus exposed to a high oxygen concentration, and, on the other hand, less diffusion of the formed hydrogen peroxide or hydroxy radicals through the layers of the valuable document is necessary.This is advantageous because it allows antimicrobial cleaning of the valuable document to be carried out continuously, without any need for intervention by the user of the valuable document, and without the need for environmental conditions to which the valuable document is not normally or only very rarely exposed, such as UV radiation.

[0016] Thus, according to a first aspect, the present invention is directed to a value document comprising a substrate with optionally two layers applied thereon opposite one another, and optionally at least one further layer, wherein the substrate and / or, if present, at least one of the two oppositely applied layers, and / or, if present, at least one of the at least one further layer contains silver-ruthenium bimetallic particles over its entire surface.

[0017] The value document can be any type of value document, for example, a security document, a banknote, or an identification document, and is preferably a banknote or an identification document, and particularly preferably a banknote. A value document typically includes at least one security feature.

[0018] The value document comprises a substrate with, optionally, two layers applied opposite one another. Any substrate suitable for value documents can be used. These substrates are known to those skilled in the art and include, for example, paper substrates, substrates based on cotton fibers or mixed fibers, where mixed fibers can in particular comprise fibers made of cotton, flax, linen, cellulose, and plastic, substrates based on plastic films, impregnated and precoated substrates. Hybrid substrates can also be used, such as paper-plastic substrates or multilayer substrates, for example film / paper / film substrates, as known from WO 2004 / 028825 A2. The value document preferably comprises a substrate based on cotton fibers or mixed fibers containing at least a cotton content.The substrate may be impregnated with any type of polymer, for example with at least one of polyvinyl alcohol, acrylates, polyester acrylates, urethane acrylates, styrene-butadienes, polyester polyurethanes and acrylic styrene polyurethanes, and is preferably impregnated with polyvinyl alcohol.

[0019] Optionally, two layers are applied opposite one another on the substrate. In a preferred embodiment, the value document according to the invention comprises a substrate with two layers applied at least partially, in particular completely, opposite one another.

[0020] The layers applied opposite the substrate are generally intended to protect the substrate, for example, by repelling dirt and / or moisture. However, they can also alternatively or additionally provide a substrate with improved adhesion for further layers, such as a printing layer. Accordingly, the layers applied opposite the substrate can be, for example, sizing layers and / or primer layers. Potential sizing layers and primer layers, and methods for their application, are known to those skilled in the art. A sizing layer and / or primer layer can be formed, for example, by a physically drying lacquer layer. "Physically drying" means that drying occurs by evaporation and / or absorption of the solvents or dispersants into the substrate.The production of suitable coatings is described, for example, in EP 2634309 A1 and WO 2004 / 072378 A1. Water-based dispersion varnishes are particularly preferred. For example, a sizing layer can contain polyvinyl alcohol and / or polyurethane. Examples of suitable primer compositions are compositions based on acrylates, polyester acrylates, urethane acrylates, styrene-butadienes, polyester polyurethanes, and acrylo-styrene polyurethanes. Water-based dispersions, in particular water-based dispersions of aliphatic components, are particularly preferred. The value document can further comprise at least one further layer, which can be applied, for example, to the print. In particular, it is preferred that the at least one further layer is a top coating. A top coating is the outermost layer of a value document, i.e., the layer that comes into direct contact with the environment.A topcoat typically provides protection against external influences such as moisture, grease, oil, solvents, and dirt, as well as physical impacts. A topcoat is preferably applied to both sides of the security and is usually applied over the entire surface.

[0021] In principle, the at least one additional layer can also be any other layer commonly used in security document printing. In the case of a top coating, it is preferred that it be a cationic or radically UV-curing layer.

[0022] Furthermore, all coating compositions described herein may independently contain the usual adjuvants, such as coalescing agents, flow control agents, wetting agents, defoamers, viscosity modifiers, dispersing agents, diluents, and crosslinking agents. Feature substances that are preferably not visually detectable, such as luminescent substances, may also be present in the compositions.

[0023] The value document according to the invention is characterized in that the substrate and / or, if present, at least one of the two oppositely applied layers, and / or, if present, at least one of the at least one further layer, contains silver-ruthenium bimetallic particles over its entire surface. "Full-surface" means that the substrate or the at least one further layer contains the silver-ruthenium bimetallic particles continuously over its entire surface.This can be in the form of a surface coating on the substrate or the at least one further layer, for example obtainable by surface impregnation or spraying of the substrate or the at least one further layer with the silver-ruthenium bimetallic particles, or in the form of a complete and continuous coating of the substrate or the at least one further layer with the silver-ruthenium bimetallic particles, for example obtainable by adding the silver-ruthenium bimetallic particles to the starting material during production of the substrate or to a coating composition for the optional at least one further layer. It is preferred that the silver-ruthenium bimetallic particles are applied in a surface coating, for example in a cover layer, on the substrate or the at least one further layer.It is also preferred that the at least one further layer be completely and continuously populated with the silver-ruthenium bimetallic particles. It goes without saying that a substrate that is interrupted at some points, for example by plastic windows or metal inserts, cannot contain silver-ruthenium bimetallic particles at these points. Likewise, if present, the at least one further layer containing silver-ruthenium bimetallic particles may not extend over the entire value document. "Full-surface" therefore does not mean that silver-ruthenium bimetallic particles must necessarily be present over the entire surface of the value document, but merely across the entire surface of the respective layer.However, it is preferred that the value document contains silver-ruthenium bimetallic particles over the entire or at least substantially the entire surface in order to ensure a uniform antimicrobial cleaning performance over the entire value document surface.

[0024] In one embodiment of the value document according to the invention, the substrate contains silver-ruthenium bimetallic particles over its entire surface. In another embodiment of the value document according to the invention, the two layers are applied opposite one another on the substrate, and at least one of the two opposite layers contains silver-ruthenium bimetallic particles over its entire surface. In a further embodiment of the value document according to the invention, at least one further layer, preferably a top coating, is present, and at least one of the at least one further layer contains silver-ruthenium bimetallic particles over its entire surface. Particularly preferably, the top coatings on both sides of the value document contain silver-ruthenium bimetallic particles over their entire surface.It is of course also possible that silver-ruthenium bimetallic particles are contained over the entire surface in more than one or even all layers of the value document, for example in the substrate and in at least one of the two oppositely applied layers, or in the substrate and in at least one of the at least one further layer, preferably a top coating or particularly preferably both top coatings, or in at least one of the two oppositely applied layers and in at least one of the at least one further layer, preferably a top coating or particularly preferably both top coatings.

[0025] The silver-ruthenium bimetallic particles are characterized by the fact that they contain silver and ruthenium, with the silver and ruthenium preferably being in electrically conductive contact for optimal catalytic effect. The bimetallic particles can consist entirely of silver and ruthenium and thus represent a compact or solid material. Nanometer- and micrometer-sized metal particles can be produced, for example, by milling, electrochemical, chemical reductive, capillary electrophoresis, hydrothermal synthesis, PVD, CVD, or sol-gel processes.

[0026] However, for cost reasons, it is preferred that the bimetallic particles have a layer of silver and ruthenium only on their surface, which is applied to a carrier material inside the bimetallic particles. This is entirely sufficient for catalytic activity and significantly reduces the requirement for silver and ruthenium for the bimetallic particles. All conceivable materials can be considered as potential carrier materials, for example, other metals; their oxides or other derivatives, metal alloys, semimetals and their compounds, nonmetals and their compounds, plastics, ceramics, or glasses. The carrier material is preferably an aluminum oxide, for example, boehmite, silicon dioxide, zirconium dioxide, titanium dioxide, steel, carbon, or cellulose. Depending on the size of the bimetallic particles and the type of carrier material, the carrier material accounts for the majority of the total weight of the bimetallic particles.For example, the proportion of carrier material in the bimetallic particles can be more than 50 wt.%, more than 70 wt.%, more than 80 wt.%, more than 90 wt.%, more than 95 wt.%, more than 98 wt.%, or even more than 99 wt.%. The proportion of silver and ruthenium in the bimetallic particle is preferably 1 to 20 wt.%, such as 2 to 18 wt.%, 3 to 17 wt.%, or 5 to 15 wt.%. All data in wt.% refer to the total weight of the bimetallic particles.

[0027] Preferably, a thin silver or silver alloy layer is first applied to the bimetallic particles on the carrier material. These are preferably applied or deposited electrolytically. Other coating processes, such as PVD, CVD, sputtering, sol, gel, and reduction processes, are also suitable plating methods. A ruthenium layer is then applied to the silver layer, with the amount of ruthenium preferably kept low relative to the amount of the silver layer, for example, in an Ag / Ru ratio of 1 / 0.001 to 1 / 0.2 or 1 / 0.005 to 1 / 0.1.The application of the rufhenium layer is preferably controlled such that the silver-containing surface is in moisture contact with the environment through continuous, preferably finely formed, free surfaces, openings, pores, cracks, gaps, or the like in the ruthenium layer, or can come into moisture contact with the environment, thereby ensuring moisture contact between the silver and the ruthenium. If the silver surface is coated with ruthenium clusters, the catalytic effect of the silver can be advantageously enhanced. Ruthenium is preferably applied in a thickness in the nanometer range, with a maximum thickness of approximately 500 nm, in particular approximately 50 nm, and a minimum thickness of approximately 5-10 nm having proven particularly suitable.

[0028] The size of the silver-ruthenium bimetallic particles is, in principle, unlimited. However, in printing ink applications, particle sizes of 5 pm or less (D90 value) have proven particularly suitable for ensuring a uniform appearance of the print produced with the printing ink. Likewise, particles with a D90 value above 5 pm, when used in the substrate or in one of the subsequent layers, tend to cause a potentially detrimental graying of the substrate or the subsequent layer. However, this can be acceptable in some applications, for example, when additional colors that mask the gray tone are present in the substrate or the subsequent layer. At the same time, the particle size should preferably not be less than 100 nm (D50 value), as otherwise the desired catalytic effect may not be sufficiently pronounced.The particle sizes of the bimetallic particles thus preferably range from 0.1 to 5 pm, preferably from 0.2 pm to 4 pm, such as from 0.3 to 3 pm, from 0.5 to 3 pm or from 1 to 3 pm, with the lower values ​​each indicating D50 values ​​and the upper values ​​each indicating D90 values. The D50 and D90 values ​​in a particle size distribution indicate the size below which 50% (D50 value) or 90% (D90 value) of the particles of the particle size distribution are located. The D50 and D90 values ​​are known to the person skilled in the art and can be determined by them without difficulty, for example using appropriate equipment from Microtrac, Inc. The surface area of ​​the silver-ruthenium bimetallic particles can range from 0.1 to 1000 m². 2 / g, for example from 0.5 to 500 m 2 / g, from 1 to 100 m 2 / g, from 2 to 50 m 2 / g, from 5 to 30 m 2 / g, or from 10 to 20 m 2 / g.

[0029] Suitable silver-ruthenium bimetallic particles are commercially available, for example under the trade names AGXX or AGXX-Hybrid from Heraeus GmbH.

[0030] The silver-ruthenium bimetallic particles can be introduced directly into the raw material composition used to produce the respective layer, for example the substrate or a further layer, or can be introduced at a later point in time into a previously prepared substrate composition or coating composition. The silver-ruthenium bimetallic particles can also be applied to the surface of the substrate or the optional further layer by impregnation or spraying. It is also conceivable to apply the silver-ruthenium bimetallic particles to the surface using coating processes such as spreading processes, flexographic printing processes, and doctor blade processes. The silver-ruthenium bimetallic particles are generally present in an amount of 0.001 to 10 wt.%, such as 0.005 to 10 wt.%, 0.01 to 10 wt.%, 0.02 to 8 wt.%, 0.03 to 7 wt.%.-%, from 0.05 to 5 wt.%, from 0.07 to 4 wt.%, 0.08 to 3.5 wt.%, from 0.1 to 3 wt.%, from 0.1 to 2 wt.%, from 0.1 to 1 wt.%, from 0.1 to 0.7 wt.% or from 0.1 to 0.5 wt.%, in each case based on the dry weight of the substrate or the respective layer, in the substrate or in the respective layer.

[0031] In principle, in addition to the silver-ruthenium bimetallic particles, at least one further antimicrobial active ingredient can also be contained in the value document according to the invention. It is particularly preferred that at least one further antimicrobial active ingredient is additionally contained in the same layer of the value document according to the invention in which the silver-ruthenium bimetallic particles are contained, for example in the substrate or, if present, in at least one of the two oppositely applied layers, and / or, if present, in at least one of the at least one further layer. In such a case, the silver-ruthenium bimetallic particles and the at least one further antimicrobial active ingredient form an active ingredient mixture.Examples of suitable additional antimicrobial agents are inorganic metal compounds, such as silver-containing compounds and substances, such as Ag(O)-containing compounds and substances, Ag(II) compounds, AgTiCh, metallic silver, as well as silver oxide and its nanoforms, metals and their metal oxides, such as copper and copper oxide as well as zinc and zinc oxide, and organic agents, such as dimethyltetradecyl [3-(trimethoxysilyl)propyl]ammonium chloride, trimethyl(tetradecyl)ammonium chloride, poly(iminocarbonimidoyliminocarbonimidoylimino-1,6-hexanediyl)hydrochloride (90), polyhexamethylene biguanide (PHMB), p-[(diiodomethyl)sulfonyl]toluene, benzalkonium chloride, methylisothiazolinone, butylbenzisothiazolinone, thiabendazole TBZ, laurylaminedipropylenediamine, pyridine-2-thiol 1-oxide, sodium salt, 3-Iodo-2-propynylbutylcarbamate, benzisothiazolinone and 4,5-dichloro-2-octyl-2H-isothiazol-3-one.Triplet chlorine or compounds that release triplet oxygen, such as photosensitizers such as phenalenone, falvin derivatives, and curcumin derivatives, can also be used as an additional active ingredient. Silver-containing compounds and substances or 3-iodo-2-propynyl butylcarbamate are preferably used as the at least one additional antimicrobial active ingredient. Silver-containing compounds and substances are particularly preferred.

[0032] The value document according to the invention can further comprise at least one print comprising at least one printing ink, preferably comprising a plurality of printing inks. A print can be either a print layer comprising a printing ink or printing ink mixture applied over the entire surface or at least partially over the entire surface of the value document, or alternatively, a print pattern obtained by applying a specific printing ink. A print can of course also comprise a plurality of print patterns comprising different printing inks, applied next to or (partially) on top of one another. Likewise, in addition to at least one print pattern comprising one printing ink, there can also be a print layer applied over the entire surface or at least partially over the entire surface of the value document. A print comprising more than one printing ink is preferred.The printing can, for example, be a background print or an intaglio print and can, for example, be applied directly to the substrate or to at least one, preferably both, of the two layers optionally applied opposite one another on the substrate or to any further layers of the value document. The printing ink used to print the value document according to the invention is not limited as such. Thus, in principle, any printing ink suitable for printing value documents can be used. Suitable printing inks are known to the person skilled in the art and are described, for example, in WO 2013178325 A2, EP 2888112 B1, DE 102012010534 A1, WO 2013178325 A2, EP 2888112 B1, WO 2018197039 A1 and EP 3660110 B1. For example, the ink can preferably be an oxidatively drying offset ink or oxidatively drying intaglio printing ink.Particularly preferred printing inks are those based on vegetable oils (e.g. linseed oil, wood oil), dissolved hydrocarbon resins and / or modified rosin resins, and / or alkyd resins, particularly high molecular weight alkyd resins, which are particularly preferred.

[0033] According to a second aspect, the present invention relates to methods for the catalytic antimicrobial, preferably antimycotic, cleaning of a value document, comprising the step of introducing silver-ruthenium bimetallic particles into at least one layer of a value document, preferably a banknote or an identification document, over the entire surface. The value document and all essential and optional components thereof, such as the substrate and the silver-ruthenium bimetallic particles, can be designed as described above in connection with the value document according to the first aspect of the present invention. The at least one layer can be the substrate and / or one of the further optional layers of the value document.The introduction of the silver-ruthenium bimetallic particles into the substrate or the respective layer can be carried out, for example, by adding the silver-ruthenium bimetallic particles to the respective raw material compositions of the respective layer and mixing them homogeneously or by superficial impregnation or spraying of the respective layer with silver-ruthenium bimetallic particles.

[0034] According to a third aspect, the present invention relates to the use of silver-ruthenium bimetallic particles for the catalytic antimicrobial, preferably antifungal, cleaning of a value document, preferably a banknote or an identification document, wherein the silver-ruthenium bimetallic particles are contained in at least one layer of the value document over its entire surface. The value document and all essential and optional components thereof, such as the substrate and the silver-ruthenium bimetallic particles, can be designed as described above in connection with the value document according to the first aspect of the present invention. The at least one layer can be the substrate and / or one of the further optional layers of the value document.

[0035] The present invention is further described below using examples. However, these examples are intended to serve only as illustrations and are not intended to limit the claimed subject matter in any way.

[0036] Examples:

[0037] The antimicrobial efficacy of substrates coated with silver-ruthenium bimetallic particles (available under the trade name AGXX from Heraeus) in various ways was investigated. Either the substrate itself or a top layer was coated with silver-ruthenium bimetallic particles. Antimicrobial efficacy was determined based on various standards (ISO 22196; A ATCC100, AATCC 30-III, and ISO 21702), with adjustments where necessary, as described below.

[0038] ISO 22196

[0039] During the test, a thin liquid film containing the bacteria (1.25 x 104 / cm2) is applied directly to the test specimens (5 cm x 5 cm). A film (4 cm x 4 cm) is then placed on top (stomacher bags) to prevent drying out. Immediately after inoculation, the bacteria are removed from the blank sample's surfaces and the covering film using ultrasound and vortexing, and the bacterial count (CFU, colony-forming unit) is determined (t24 value). Another set of blank samples and antimicrobially treated samples are incubated with bacteria in the liquid film (with a covering film) in a humid environment at 37°C. After at least 24 hours, surviving bacteria are removed from the sample surfaces and the covering film using ultrasound and vortexing, and the bacterial count is determined (t24 value).

[0040] AATCC100

[0041] The bacterial inoculum (2.5 x 105 CFU (colony forming unit) / ml) is applied directly to the test specimens (16 cm 2 The samples are then incubated with bacteria in a humidified environment at 37°C for 18 hours (standard). One set of samples (reference) is processed immediately after inoculation (tO value). For this purpose, the bacteria are removed from the samples using ultrasound and vortexing, and the bacterial count (CFU, colony-forming unit) is determined.

[0042] AATCC 30-III

[0043] The test was conducted in two runs according to AATCC 30:2017, Test Method III, using a 4 cm diameter round specimen. The specimens were placed on mineral salt agar with 3% glucose. 0.5 ml of a spore suspension was evenly distributed over the culture medium, and 0.2 ml of the spore suspension was pipetted onto the specimen. The specimens were incubated on the culture medium at 30°C for 7 days. Fungal growth was then assessed visually and microscopically and documented photographically.

[0044] ISO 21702:

[0045] Tests according to ISO 21702 followed the standard with the following test parameters: microorganism used: Bovine coronavirus; inoculum volume: 400 μl; test body size: 4 x 4 cm 2 = 16 cm 2 ; Contact time: 24 hours; Contact temperature: 25°C ± 1°C; Relative humidity: 90% ± 5%.

[0046] Example 1: Equipment Substrate - Bactericide

[0047] A substrate (standard cotton banknote substrate with 1.67 wt.% polyvinyl alcohol (PVA) impregnation) was coated with silver-ruthenium bimetallic particles at a concentration of 1.1 wt.%, based on the total surface area of ​​the PVA impregnation of the substrate. The bactericidal properties of the substrate were determined according to the AATCC 100 test using S. aureus and E. coli bacteria and a test time of 24 hours. The measured efficacy after the test period was 99.9% against both bacteria.

[0048] Example 2: Equipment varnish (top coat) - bactericide

[0049] Two topcoat coatings were prepared. A radically curable coating (TOPnote®, available from Giesecke+Devrient Currency Technologie GmbH) was coated with silver-ruthenium bimetallic particles at concentrations of 0.1 and 0.2 wt.%, respectively, based on the total coating weight. The coatings were each applied to a polymer substrate (Guardian™, available from CCL Secure). The bactericidal properties of the resulting topcoats were determined according to the ISO 22196 test using S. aureus and E. coli bacteria and a test time of 24 hours. The measured effectiveness after the test period was 99.9% against both bacteria for both coatings.

[0050] Example 3: Finish varnish (top coat) - bactericide

[0051] Two topcoats were prepared. A radically curable topcoat (TOPnote®, available from Giesecke+Devrient Currency Technologie GmbH) was coated with silver-ruthenium bimetallic particles at concentrations of 0.1 and 0.2 wt.%, respectively, based on the total weight of the topcoat. The topcoats were each applied to a paper substrate (standard cotton banknote paper, available from Papierfabrik Louisenthal). The bactericidal properties of the resulting topcoats were determined according to the AATCC100 test using the bacteria S. aureus and E. coli and a test time of 24 hours. The measured efficacy after the test period was 99.9% against both bacteria for both topcoats.

[0052] Example 4: Finish varnish (top coat) - bactericide

[0053] Two topcoats were prepared. A radically curable topcoat (TOPnote®, available from Giesecke+Devrient Currency Technologie GmbH) was coated with silver-ruthenium bimetallic particles at concentrations of 0.1 and 0.2 wt.%, respectively, and 1 wt.% of 3-iodo-2-propynyl butylcarbamate (IPBC), each based on the total weight of the topcoat. The topcoats were each applied to a paper substrate (standard cotton banknote paper, available from Papierfabrik Louisenthal). The bactericidal properties of the resulting topcoats were determined according to the AATCC100 test using the bacteria S. aureus and E. coli and a test time of 24 hours. The measured efficacy after the test period was 99.9% against both bacteria for both topcoats.

[0054] Example 5: Finish varnish (top coat) - fungicide

[0055] A topcoat was prepared. A radically curable topcoat (TOPnote®, available from Giesecke+Devrient Currency Technologie GmbH) was coated with silver-ruthenium bimetallic particles at a concentration of 0.2 wt.%, based on the total weight of the topcoat. The topcoat was applied to a paper substrate (standard cotton banknote paper, available from Papierfabrik Louisenthal). The fungicidal properties of the resulting topcoat were determined according to the AATCC 30-III test using the bacterium A. Brasiliensis and a test time of 7 days. No growth was observed on the sample after the test period. An uncoated sample was completely protected.

[0056] Example 6: Finish varnish (top coat) - fungicide

[0057] A topcoat was prepared. A radically curable topcoat (TOPnote®, available from Giesecke+Devrient Currency Technologie GmbH) was coated with silver-ruthenium bimetallic particles at a concentration of 0.2 wt.% and 1 wt.% 3-iodo-2-propynyl butylcarbamate (IPBC), each based on the total weight of the topcoat. The topcoat was applied to a paper substrate (standard cotton banknote paper, available from Papierfabrik Louisenthal). The fungicidal properties of the resulting topcoat were determined according to the AATCC 30-III test using the bacterium A. Brasiliensis and a test time of 7 days. No growth was observed on the sample after the test period. An uncoated sample was completely protected.

[0058] Example 7: Finish varnish (top coat) - virucidal

[0059] A topcoat was prepared. A radically curable topcoat (TOPnote®, available from Giesecke+Devrient Currency Technologie GmbH) was coated with silver-ruthenium bimetallic particles at a concentration of 0.2 wt.%, based on the total weight of the topcoat. The topcoat was applied to a polymer substrate (Guardian™, available from CCL Secure). The virucidal properties of the resulting topcoats were determined according to the ISO 21702 test using the bovine coronavirus pathogen and a test duration of 24 hours. The measured efficacy of the topcoat after the test duration was 99%.

[0060] Example 8: Finish varnish (top coat) - virucidal

[0061] A topcoat was prepared. A radically curable topcoat (TOPnote®, available from Giesecke+Devrient Currency Technologie GmbH) was coated with silver-ruthenium bimetallic particles at a concentration of 0.2 wt.% and 1 wt.% 3-iodo-2-propynyl butylcarbamate (IPBC), each based on the total weight of the topcoat. The topcoat was applied to a polymer substrate (Guardian™, available from CCL Secure). The virucidal properties of the resulting topcoats were determined according to the ISO 21702 test using the bovine coronavirus germ and a test time of 24 hours. The measured efficacy of the topcoat after the test period was 99%.

[0062] Example 9: Equipment Substrate - Virucide

[0063] A substrate (standard cotton banknote substrate impregnated with 1.67 wt.% polyvinyl alcohol (PVA)) was coated with silver-ruthenium bimetallic particles at a concentration of 1.1 wt.%, based on the total surface area of ​​the PVA impregnation. The virucidal properties of the substrate were determined according to the ISO 21702 test using the bovine coronavirus pathogen and a test time of 24 hours. The measured efficacy of the varnish after the test period was 99.8%.

Claims

CLAIMS 1. A value document comprising a substrate with optionally two layers applied thereon opposite one another, and optionally at least one further layer, wherein the substrate and / or, if present, at least one of the two oppositely applied layers, and / or, if present, at least one of the at least one further layer contains silver-ruthenium bimetallic particles over its entire surface.

2. A value document according to claim 1, wherein the substrate contains silver-ruthenium bimetallic particles over its entire surface.

3. A value document according to claim 1 or 2, wherein the two layers applied opposite one another are present, and at least one of the two oppositely applied layers contains silver-ruthenium bimetallic particles over its entire surface.

4. A value document according to any one of claims 1-3, wherein at least one further layer is present and at least one of the at least one further layer contains silver-ruthenium bimetallic particles over its entire surface.

5. A value document according to any one of claims 1-4, wherein the silver-ruthenium bimetallic particles have a diameter of at most 5 pm.

6. A value document according to any one of claims 1-5, wherein at least one further layer is present, and at least one of the at least one further layer is a cationically or radically UV-curing top coating which contains silver-ruthenium bimetallic particles over its entire surface.

7. A value document according to any one of claims 1-6, wherein the substrate is impregnated with at least one of polyvinyl alcohol, acrylates, polyester acrylates, urethane acrylates, styrene-butadienes, polyester polyurethanes and acrylo-styrene polyurethanes, and preferably with polyvinyl alcohol.

8. A value document according to any one of claims 1-7, wherein the value document is a banknote or an identification document.

9. A method for the catalytic antimicrobial cleaning of a value document, comprising the step of introducing silver-ruthenium bimetallic particles into at least one layer of a value document, preferably a banknote or an identity document.

10. Use of silver-ruthenium bimetallic particles for the catalytic antimicrobial cleaning of a value document, preferably a banknote or an identity document, wherein the silver-ruthenium bimetallic particles are contained over the entire surface of at least one layer of the value document.