EP4070963A1 - Valuable document substrate and composition - Google Patents

Abstract

The invention relates to a value document substrate for the production of banknotes, identity documents or certificates, which is at least partially provided with an antimicrobial coating, characterized in that the coating has microcapsules containing a disinfectant.

Description

The invention relates to a value document substrate, in particular a fit document of value such as a banknote, or a security paper that is not yet fit for circulation, in particular unprinted, for producing a document of value such as a banknote. The invention further relates to a composition suitable for coating a value document substrate.

During their circulation, documents of value, such as banknotes, are exposed to different types of heavy loads, which limit their period of circulation. The period in which a banknote remains in circulation depends to a large extent on how much it is used. Certain denominations are preferred in retail and therefore have a shorter circulation time due to the greater impact of environmental influences. One reason for the limitation of the circulation time is mechanical stresses caused by abrasion, folding or creasing. The main reason for the limited circulation time of banknotes is their early soiling.

Dirt can be liquid or solid, and liquid dirt can be oily or watery. A special type of "pollution" is contamination with pathogenic microorganisms such as bacteria, viruses, fungi or other pathogenic agents.

Antimicrobial coatings for finishing the surface of documents of value are known, see for example EP 2 634 309 A1 . the EP 2 634 309 A1 describes an antimicrobial coating containing multiple antimicrobial agents, eg, 1,2-benzisothiazol-3(2H)-one (BIT) and a silver-containing antimicrobial agent. An antimicrobial, in particular antibacterial, antifungal or antiviral agent can optionally be introduced into the substrate itself, for example in the course of the so-called "sizing" a security paper. Optionally, one antimicrobial agent can be provided in the substrate and a second antimicrobial agent can be provided in an antisoiling coating.

It has been found that the antimicrobial coatings known in the prior art are consumed as a result of diffusion processes, particularly during prolonged storage, and therefore lose their antimicrobial effectiveness.

In this respect, there is a need to protect documents of value, and in particular the heavily used banknotes, against antimicrobial soiling and contamination of any kind in the long term, in order to thereby increase the period in circulation and prevent the transmission of diseases or any other pathogenic effect of the documents of value.

It is therefore the object of the present invention to specify a value document substrate which avoids the disadvantages of the prior art.

The object of the present invention is also to specify a composition suitable for coating the value document substrate.

The objects are solved by the feature combinations defined in the independent claims. Particular developments of the invention are specified in the relevant dependent claims.

Summary of the Invention

• 1. (First aspect of the invention) value document substrate for the production of banknotes, identity documents or certificates, which is at least partially provided with an antimicrobial coating, characterized in that the coating has microcapsules with disinfectant contained therein.
• 2. (Preferred embodiment) Value document substrate according to Clause 1, wherein the microcapsules are designed in such a way that the capsule wall ruptures under mechanical stress or through the action of high-energy radiation, in order in this way to allow the ingredients contained within the capsule to escape.
• 3. (Preferred embodiment) A value document substrate according to clause 1 or 2, wherein the disinfectant is liquid or gaseous.
• 4. (Preferred embodiment) value document substrate according to clause 3, wherein the disinfectant is liquid and is an alcohol, in particular phenol or a phenol derivative, a quaternary amine, a nitrosamine or a complex-bound nitrosamine or a hydrogen peroxide solution; or wherein the disinfectant is liquid and these are encapsulated metallic nanopigments, e.g. silver, copper or zinc oxide, which are dispersed in an aqueous and/or alcoholic solvent, the alcoholic solvent being in particular glycerol.
• 5. (Preferred embodiment) A value document substrate according to clause 3, wherein the disinfectant is gaseous and is ozone.
• 6. (Preferred embodiment) value document substrate according to one of clauses 1 to 5, wherein the disinfectant in combination with an additional antimicrobial agent preferably selected from the group consisting of 1,2-benzisothiazol-3(2H)-one (BIT), 3-iodo-2-propynylbutylcarbamate (IPBC), a silver containing compound, a silver salt such as silver phosphate glass and a combination of two or more of the above elements.
• 7. (Preferred embodiment) Value document substrate according to one of clauses 1 to 6, wherein the capsules have a particle size D50 in a range from 10 μm to 30 μm.
• 8. (Preferred embodiment) Value document substrate according to one of clauses 1 to 7, wherein the substrate is a paper substrate, a foil substrate or polymer substrate or a composite foil substrate, wherein the composite foil substrate in particular has a core based on paper and outer layers based on foils or has a core made of a plastic material and outer layers based on paper or a composite of at least two film layers.
• 9. (Preferred embodiment) Value document substrate according to one of clauses 1 to 8, wherein the coating is a protective layer based on a radiation-curing composition and is preferably based on a cationically crosslinking UV varnish or a radically crosslinking UV varnish.
• 10. (Preferred embodiment) Value document substrate according to one of clauses 1 to 9, wherein the coating is an ink-receptive layer and is preferably based on a solvent-based or radiation-curing or aqueous composition, with an aqueous composition being particularly preferred.
• 11. (Preferred embodiment) Value document substrate according to one of clauses 1 to 10, wherein the formulation contains at least one other antimicrobial and/or antibacterial and/or antiviral active substance, which preferably simultaneously fulfills the function of a stabilizer, a photoinitiator, a rheological additive or a filler .
• 12. (Second aspect of the invention) A composition for coating a substrate of value according to any one of clauses 1 to 11, comprising microcapsules with disinfectant contained therein.

Detailed Description of the Invention

“Antimicrobial” in the context of the present invention means that it is effective against microorganisms, the effect ideally consisting in killing the microorganisms, but it can also consist in inhibiting the growth and multiplication of the microorganisms.

"Microorganisms (microbes)" within the meaning of the invention are, in particular, bacteria, fungi, such as molds and yeasts, and viruses.

The invention is based on the finding of using encapsulated disinfectants in a composition suitable for coating documents of value. The encapsulating material breaks open in the course of a mechanical stress during the circulation of documents of value, in particular during the circulation of banknotes, and releases the disinfectant. A liquid or gaseous disinfectant is particularly suitable as the disinfectant disinfectant. In particular, the encapsulated disinfectant can be used in combination with additional antimicrobial agents, eg 1,2-benzisothiazol-3(2H)-one (BIT), 3-iodo-2-propynylbutylcarbamate (IPBC), a silver-containing compound and/or a silver salt such as silver phosphate glass. As a result of the encapsulation, the disinfecting and antimicrobial effect of the value-document coating is prolonged over the course of the storage, transport and circulation of the value-document.

Suitable liquid disinfectants include, for example, alcohol, mixtures of alcohol and other disinfectants, and hydrogen peroxide solution. With regard to gaseous disinfectants, ozone and an ozone/air mixture are suitable.

According to a variant, the disinfectant is liquid and is in particular encapsulated metallic nanopigments, e.g. silver, copper or zinc oxide, dispersed in an aqueous and/or alcoholic solvent, the alcoholic solvent being in particular glycerol. By the term "alcoholic solvent" is meant an alcohol such as ethanol, propanol, butanol, phenol, a phenol derivative, glycol and/or glycerine. However, the solvent can also be in the form of an aqueous-alcoholic solvent, i.e. in the form of a mixture of an alcohol and water.

The capsules are broken open, for example, by mechanical pressure, by abrasion, by shearing forces, by means of cutting and/or by means of squeezing during the circulation of the document of value.

The capsules preferably have a particle size D50 in a range from 10 μm to 30 μm.

With regard to the production of the capsules, a classic in situ polymerisation, e.g. oil in water, is less preferred as an encapsulation method. For example, with respect to the manufacture of the capsules, it is convenient to incorporate liquid alcohol components into a crosslinked polymer, e.g., polyacrylic acid, and to incorporate the product thus obtained into a varnish. The advantage here is that no capsule has to be broken open to release the disinfectant, but the release can take place in the sense of a gradient.

In the case of UV varnishes, it is advantageous that encapsulated ozone is not already released during the application of the varnish to the document of value substrate, because otherwise the crosslinking of the monomers and prepolymers in the course of UV curing would be impaired, reduced or even prevented.

Encapsulation, in particular of hydrogen peroxide, alcohols and/or phenols, can also be carried out using a microfluidic method. Here, for example, in a first phase, an emulsion consisting of alcohol and a hydrophobic capsule wall material, for example based on UV-curing acrylates or PU acrylates, can be produced. In a second phase, a second emulsion consisting of the first emulsion in a hydrophilic carrier medium, eg water, can be prepared. In a third phase, the capsule wall material, which preferably cures with UV radiation, can still be crosslinked or at least pre-crosslinked in the carrier medium. The capsules produced are then separated from the hydrophilic carrier medium, namely mechanically by means of sieves, by sedimentation, by means of thermal drying or by means of freeze drying. The capsule wall thickness and the particle size of the capsules are controlled by the parameters material ratio, flow rate (which can be influenced by the pump pressure), chip design and surface tension of the transport tubes.

Encapsulation of ozone in particular can be achieved, for example, by filling a glass container or a stainless steel container with a capsule wall material in a first phase. Ozone is then introduced, with the air being substituted by ozone because ozone is heavier than air. The ozone is then worked into the hydrophobic capsule wall material by means of a propeller stirrer or by means of a dissolver disk until finely distributed ozone bubbles are present in the capsule wall material. Thereafter, the excess ozone is evacuated. Water can then be introduced so that an emulsion of the capsule wall material with the encapsulated ozone is formed. This is followed by drying.

According to a further encapsulation method, a middle nozzle and an outer annular nozzle can be used. Ozone flows in from the middle nozzle, and the capsule wall material flows in from the outer nozzle. A pulsed gas jet and a pulsed capsule wall material jet produce particles with enclosed ozone. Conveniently, the pulse frequency has the same value in both cases, but the pulse duration for the inner nozzle is expediently shorter in order to enable closure. The closure can also be positively influenced by an additional pulsed lateral movement of the nozzle carrier (especially with the same pulse frequency). The drying of Capsule wall material can be done by means of UV radiation or in vacuo by means of electron beams or in a carrier medium.

Another possibility for the encapsulation is based on the binding of the ozone in a porous carrier, e.g. Metal-organic frameworks or framework compounds are microporous materials that are made up of inorganic structural units, so-called SBUs (secondary building units) and organic molecules or linker molecules as connecting elements between the inorganic structural units. Metal-organic frameworks are often, but not necessarily, crystalline. MOFs are coordination polymers or coordination networks with an open framework that may contain pores. MOFs are usually based on so-called Werner complexes. After synthesis, the pores of the three-dimensional structures are filled with guest molecules, e.g. solvent molecules or unreacted linker molecules. The pores can be made accessible by removing the guest molecules, e.g. by heating, in a vacuum or by a combination of both measures. Potential areas of application can be found in gas storage (e.g. hydrogen, methane), in material separation, in sensor technology and in catalysis.

• 50% bis 80% Präpolymere;
• 10% bis 30% Reaktivverdünner;
• 1% bis 20% Kapseln mit darin enthaltenem antimikrobiellem Wirkstoff;
• 3% bis 8% Photoinitiator;
• 0% bis 3% Wachs;
• 0% bis 1% Anti-Slip-Mittel;
• 0% bis 1% Benetzungsmittel;
• 0% bis 1,5% Entschäumer;
• 0% bis 5% Trocknungsbeschleuniger;
• 0% bis 5% Stabilisator, vorzugsweise gewählt von der Gruppe der Phenolderivate (z.B. BHT, MEHQ);
• 0% bis 20% Stabilisator, vorzugsweise gewählt von der Gruppe der HALS (z.B. Tinuvin 292).

An example of a UV-curing radical varnish is based on the following composition (unless otherwise stated, in % by weight):

• 50% to 80% prepolymers;
• 10% to 30% reactive diluent;
• 1% to 20% capsules containing antimicrobial agent;
• 3% to 8% photoinitiator;
• 0% to 3% wax;
• 0% to 1% anti-slip agent;
• 0% to 1% wetting agent;
• 0% to 1.5% defoamer;
• 0% to 5% drying accelerator;
• 0% to 5% stabilizer, preferably selected from the group of phenol derivatives (e.g. BHT, MEHQ);
• 0% to 20% stabilizer, preferably selected from the group of HALS (e.g. Tinuvin 292).

Coated bacteriophages are inactivated in particular by butylated hydroxytoluene or butylated hydroxyanisole. Furthermore, butylated hydroxytoluene inactivates lipid-containing viruses. In addition, according to an alternative, nitrosyl radical, which has an antiviral effect, can conveniently be added.

• 55% Polyester-Acrylat, z.B. Laromer PE 55 F der Firma BASF;
• 5% Kapseln mit darin enthaltenem antimikrobiellem Wirkstoff;
• 10% Acrylsäureester, z.B. Laromer TMPTA der Firma BASF;
• 21% Acrylsäureester (Reaktivverdünner), z.B. Laromer HDDA der Firma BASF;
• 5% Photoinitiator, z.B. Darocure 1173 der Firma CIBA;
• 3% reaktives Amin als Trocknungsbeschleuniger, z.B. Ebecryl P 115 der Firma UCB;
• 0,5% Entschäumer auf Silikonbasis, z.B. Coatosil 100 E;
• 0,5 % Anti-Slip-Mittel, z.B. Dow Corning 57 der Firma DOW.

A particular example of a radical paint system is based on the following composition (unless otherwise stated, in % by weight):

• 55% polyester acrylate, for example Laromer PE 55 F from BASF;
• 5% capsules with antimicrobial agent inside;
• 10% acrylic acid ester, for example Laromer TMPTA from BASF;
• 21% acrylic acid ester (reactive diluent), for example Laromer HDDA from BASF;
• 5% photoinitiator, for example Darocure 1173 from CIBA;
• 3% reactive amine as a drying accelerator, for example Ebecryl P 115 from UCB;
• 0.5% silicone-based defoamer, eg Coatosil 100 E;
• 0.5% anti-slip agent, for example Dow Corning 57 from DOW.

• 15% Polyvinylalkohol, z.B. 4-88 der Firma Mowiol;
• 5% Kapseln mit darin enthaltenem antimikrobiellem Wirkstoff;
• 1% Entschäumer, z.B. 093 der Firma Byk;
• 79% Wasser.

A particular example of a polyvinyl alcohol sizing has the following composition:

• 15% polyvinyl alcohol, eg 4-88 from Mowiol;
• 5% capsules with antimicrobial agent inside;
• 1% defoamer, for example 093 from Byk;
• 79% water.

Suitable substrates are, in particular, paper substrates, film substrates or polymer substrates and so-called hybrid substrates, which are preferably to be understood as meaning film composite substrates that have either a core based on paper and films as outer layers or a core made of a film-like plastic material and outer layers based on paper. However, the combination of several film layers based on one or different polymer types is also possible. Paper or fiber composites and foils can be based on artificial (e.g. biaxially oriented polypropylene (BOPP), polyethylene (PE), polyamide (PA), polyethylene terephthalate (PET)) and biological polymers (e.g. polysucrose, polylactate). It is preferred to use substrates based on cotton fibers (i.e. the polymer is polysucrose or cellulose).

The substrate can have specific coatings, impregnations or also imprints and/or security elements or film elements.

In the case of a foil substrate or polymer substrate or a composite substrate with a core of paper and outer layers of foils, it is expedient to apply one or more coatings to the foils, which ensure adhesion of the print to be applied to the respective substrate. This layer applied to the films is usually referred to as the ink acceptance layer. In the case of a paper substrate, ink acceptance layers are usually not necessary, but the paper substrate can be coated completely or partially in order to provide it with certain properties, e.g. luminescent properties due to applied luminescent substances, or to make it antiviral/antibacterial. Ink acceptance layers are usually based on fillers, such as titanium dioxide, aluminum oxide or silicon dioxide pigments, incorporated in a suitable binder.

The composition according to the invention, which is suitable for coating a value-document substrate, can be applied to the value-document substrate, for example, by means of a flexographic printing process, screen printing process or gravure printing process.

The value document substrate is preferably coated in the final step of value document production, in the case of banknotes after (intaglio) printing. In particular, the imprinting of a serial number can, if required, only take place after the composition according to the invention has been applied to the value document substrate.

Advantageously, the coatings each cover the entire surface of the value document substrate, it being of course also possible in principle to coat the substrates on only one surface and/or only over part of the surface.

Furthermore, according to a preferred embodiment, the coating of the value document substrate can be such that it has an antibacterial and/or antiviral surface, which is based, for example, on a UV or electron beam-curing protective lacquer formulation, the formulation containing at least one antibacterial and/or antiviral active ingredient contains, which preferably simultaneously fulfills the function of a stabilizer, a photoinitiator, a rheology additive or a filler. The stabilizer can be selected, for example, from the group of so-called HALS (hindered amine light stabilizers), in particular in a weight proportion in a range from 0.01% to 20%, and/or a phenol derivative, in particular in a weight proportion in a range of up to 5%, and/or a nitrosamine, in particular in a proportion by weight of up to 5%. According to a special variant, the HALS stabilizer is built into the cured polymer film as a co-crosslinking component, for example in the form of a polyol component. The incorporation of a HALS stabilizer as a co-crosslinking component in a polymer is, for example, from EP 0 839 844 A1 known. A tetramethylpiperidine derivative, for example, can be used as the HALS stabilizer. In the case of the simultaneous function of the active ingredient as a photoinitiator, a coinitiator from the group of tertiary amines can be used, for example, in particular in a proportion by weight in a range of up to 10%.

Further exemplary embodiments and advantages of the invention are explained below in connection with the figure.

It shows:
1 a value document substrate according to the invention, in the present case a bill, according to one embodiment.

the figure 1 shows a value document substrate 1 according to the invention, in the present case a bank note, according to an exemplary embodiment in a cross-sectional view. The banknote 1 is based on a paper substrate 2, which has a coating 3 or 4, namely a lacquer, on both its upper and lower main surface.

The paper substrate 2 was coated by means of a flexographic printing process, namely in the final step after the paper substrate had been printed with a background print and an intaglio printing pattern, but before a serial number was printed.

The lacquer used for coating the value document substrate 1 contained microcapsules filled with disinfectant with a particle size D50 of 20 μm. A mixture of ethanol and 1,2-benzisothiazol-3(2H)-one (BIT) served as a disinfectant as an additional antimicrobial agent.

• 65% Präpolymere;
• 20% Reaktivverdünner;
• 10% Kapseln mit darin enthaltenem antimikrobiellem Wirkstoff;
• 5% Photoinitiator;
• 1,5% Wachs;
• 0,5% Anti-Slip-Mittel;
• 0,5% Benetzungsmittel;
• 1% Entschäumer;
• 2,5% Trocknungsbeschleuniger;
• 2,5% Phenolderivat-Stabilisator (BHT);
• 10% Stabilisator, gewählt von der Gruppe der HALS (z.B. Tinuvin 292).

The UV curing radical varnish used for the coating was based on the following composition:

• 65% prepolymers;
• 20% reactive diluent;
• 10% capsules containing antimicrobial agent;
• 5% photoinitiator;
• 1.5% wax;
• 0.5% anti-slip agent;
• 0.5% wetting agent;
• 1% defoamer;
• 2.5% drying accelerator;
• 2.5% phenol derivative stabilizer (BHT);
• 10% stabilizer chosen from the group of HALS (e.g. Tinuvin 292).

The capsules were produced by introducing the liquid ingredients into a crosslinked polymer, in this example polyacrylic acid.

Claims (12)

Document of value substrate for the production of banknotes, identification documents or certificates, which is at least partially provided with an antimicrobial coating, characterized in that the coating has microcapsules containing a disinfectant. Value document substrate according to claim 1, wherein the microcapsules are designed in such a way that the capsule wall ruptures under mechanical stress or under the action of high-energy radiation, in order in this way to allow the contents contained within the capsule to escape. Value document substrate according to claim 1 or 2, wherein the disinfectant is liquid or gaseous. Value document substrate according to claim 3, wherein the disinfectant is liquid and is an alcohol, in particular phenol or a phenol derivative, a quaternary amine, a nitrosamine or a complex-bound nitrosamine or a hydrogen peroxide solution; or wherein the disinfectant is liquid and these are encapsulated metallic nanopigments, e.g. silver, copper or zinc oxide, which are dispersed in an aqueous and/or alcoholic solvent, the alcoholic solvent being in particular glycerol. A value document substrate according to claim 3, wherein the disinfectant is gaseous and is ozone. Value document substrate according to one of claims 1 to 5, wherein the disinfectant is used in combination with an additional antimicrobial agent, which is preferably selected from the group consisting of 1,2-benzisothiazol-3(2H)-one (BIT), 3-iodo-2 -propynylbutylcarbamate (IPBC), a silver-containing compound, a silver salt such as silver phosphate glass and a combination of two or more of the above elements. A value document substrate according to any one of claims 1 to 6, wherein the capsules have a particle size D50 in a range from 10 µm to 30 µm. Value document substrate according to one of claims 1 to 7, wherein the substrate is a paper substrate, a foil substrate or polymer substrate or a composite foil substrate, wherein the composite foil substrate in particular has a core based on paper and outer layers based on foils or a core made of a plastic material and Paper-based outer layers or a composite of at least two film layers. Value document substrate according to one of claims 1 to 8, wherein the coating is a protective layer based on a radiation-curing composition and is preferably based on a cationically crosslinking UV varnish or a radically crosslinking UV varnish. A document of value substrate according to any one of claims 1 to 9, wherein the coating is an ink-receptive layer and is preferably based on a solvent-based or radiation-curing or aqueous composition, an aqueous composition being particularly preferred. A document of value substrate according to any one of claims 1 to 10, wherein the formulation contains at least one other antimicrobial and/or antibacterial and/or antiviral active substance which preferably simultaneously fulfills the function of a stabilizer, a photoinitiator, a rheological additive or a filler. A composition for coating a substrate of value according to any one of claims 1 to 11, comprising microcapsules with disinfectant contained therein.

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