EP4126558A1

EP4126558A1 - Valuable document substrate and method for disinfection

Info

Publication number: EP4126558A1
Application number: EP21716262.7A
Authority: EP
Inventors: Christoph Mengel; Geza MURVAI; Bernhard Wiedner; Patrick Renner; Peter Schiffmann
Original assignee: Giesecke and Devrient Currency Technology GmbH
Current assignee: Giesecke and Devrient Currency Technology GmbH
Priority date: 2020-04-03
Filing date: 2021-03-25
Publication date: 2023-02-08
Also published as: WO2021197663A1

Abstract

The invention relates to a value document substrate having two opposing main surfaces, at least one of the two main surfaces having a photosensitizer for generating singlet oxygen.

Description

Value document substrate and method for disinfecting

The invention relates to a value document substrate, in particular a fit document of value such as a banknote, or a not yet fit for circulation, in particular unprinted, security paper for generating a document of value such as a bank note. The invention also relates to a method for disinfecting the value document substrate.

In the production of documents of value, e.g. banknotes, the printing process usually takes place in several printing steps, whereby a variety of successive printing and finishing processes can be used. One of the first steps here is usually a single-color or multi-color background printing using the offset and / or letterset process.

The printing equipment used for this can vary greatly and is dependent on the following parameters:

- the security colors or security pigments used;

- the type of (paper) substrate used (e.g. substrates based on cotton fibers; substrates based on mixed fibers, mixed fibers being in particular cotton, flax, linen, cellulose and synthetic fibers; substrates based on plastic films; impregnated and precoated substrates);

the provision of substrates to be printed which have an inhomogeneous structure (e.g. paper substrates provided with a film element; partially preprinted substrates; substrates with flat elements partially applied on the basis of screen printing);

the provision of substrates to be printed which have a different pH value and / or a different paper moisture content at different points, with differently rough and porous surfaces also having an influence here. While production errors that lead to a visible deterioration in the printing result can be detected and corrected at the printing press (e.g. the ink feed), there is a risk of production errors affecting the substrate drying and / or the substrate dimensions, which will affect the further production process slow it down considerably and also increase the amount of waste. The different printing equipment required for printing also has a strong influence on the behavior of the printed sheets in the subsequent printing steps. Pressure steps that add heat lead to substrate shrinkage. In the case of publications that are carried out under high mechanical pressure, dimensional changes (in particular dimension enlargements) appear on the substrate. In particular, intaglio printing, which is widespread in security and security printing, puts a special strain on the substrate and layers of paint, so that adequate drying is essential.

If the dimensional changes on the substrate exceed certain tolerance limits, often the only thing left is the reprint with a changed printing equipment. Alternatively, the printing equipment of the subsequent printing steps can be adapted, which is associated with a lot of effort and high costs.

Insufficient drying of a printed substrate as a result of a problematic color formulation or as a result of a substrate that does not set can be accelerated in part by the supply of heat. However, the heating of printed products often leads to a change in the dimensions of the printed substrate that is difficult to control. This is particularly the case with cellulose, cotton and other paper substrates, where the heat input leads to a loss of moisture. As a consequence ge it is often not possible to keep the register in the following publications. The effect also occurs when using plastic substrates or hybrid substrates (for example multi-layer film / paper / film substrates, as are known from WO 2004/028825 A2). Another disadvantage is that the depositing of printing ink within a stack of documents of value cannot be significantly improved in this way. The depositing of printing ink here refers to the phenomenon that the still wet printing ink is reproduced on the next printed sheet and there disturbs the printing result.

The drying of a printed substrate can also be accelerated by adding metal-containing drying agents. Oxidative drying printing inks (i.e. printing inks that do not belong to the UV inks or UV varnishes) usually contain a drying agent or siccative. Drying agents are in particular organic salts of certain metals such as cobalt (e.g. cobalt octoate, cobalt naphthenate), manganese, calcium (e.g. calcium octoate), zirconium or cerium. Metal-containing drying agents only develop their effect in the presence of oxygen. Provided that storage and transport are largely carried out in the absence of air, a drying agent can be incorporated into the paint at the factory. The disadvantage of these drying agents, however, is that the use of (heavy) metal compounds is problematic for reasons of work-related safety and health hazards. A low use concentration would therefore be desirable, but this leads to long drying times.

The drying of a printed substrate can also be accelerated by adding peroxide-containing substances such as inorganic or organic peroxides. When they disintegrate, these cause radical harm free of substances and thus accelerate the oxidative drying of the paint layer. This also works in places where there is a lack of air or oxygen, consequently also in the case of substrates that do not turn away and in high or large-area stacks of valuable documents. However, the disadvantage is that peroxide-containing substances can only be added to the ink relatively shortly before printing, because the ink cannot be stored for a longer period of time due to the chemical reaction that begins when the peroxide is added.

The drying of a printed substrate can also be accelerated by using UV-drying background colors or hybrid UV systems instead of oxidative drying systems. Such inks are, however, significantly more expensive, often have sensitizing properties and, under certain circumstances, have poor overprintability. In addition, they only have a limited shelf life as a finished paint. The same applies to innovative hybrid ink formulations that contain both conventional, oxidatively drying ink components and UV-curing ink components.

According to the prior art WO 2013/178325 A2, it has been shown, interestingly, that the drying of conventional undercoat colors is also accelerated with UV radiation.

The present invention is based on the object of providing a value document substrate such as a security paper or a value document which, compared to the value document substrates known in the prior art, has improved properties in terms of its production and subsequent circulation. The present invention is based in particular on the object of providing a document of value substrate such as for example to provide a security paper or a document of value which has an advantageous drying ability during printing.

The above object is achieved by the combination of features defined in the main claim and in the subordinate main claim. The dependent claims represent preferred embodiments.

Summary of the invention

1. (First aspect of the invention) document of value substrate with two opposing main surfaces, at least one of the two main surfaces having a photosensitizer for generating singlet oxygen. 2. (Preferred embodiment) document of value substrate according to clause 1, wherein both main surfaces of the document of value substrate each have a photosensitizer for generating singlet oxygen.

3. (Preferred embodiment) document of value substrate according to clause 1 or 2, the main surface of the document of value substrate or both main surfaces of the document of value substrate being provided over the entire surface with the photosensitizer for generating singlet oxygen.

4. (Preferred embodiment) Document of value substrate according to one of the claws 1 to 3, the photosensitizer being incorporated in a coating, preferably a lacquer, for generating singlet oxygen. 5. (Preferred embodiment) document of value substrate according to one of clauses 1 to 4, the document of value substrate being a security paper for the production of documents of value, in particular banknotes.

6. (Preferred embodiment) document of value substrate according to one of clauses 1 to 3, the photosensitizer for generating singlet oxygen being part of a (in particular conventional or physically drying) background color with which the document of value substrate on one of its two main surfaces or on both Main areas are printed in the form of a background print.

7. (Preferred embodiment) document of value substrate according to one of clauses 1 to 3, the photosensitizer for generating singlet oxygen being part of a (in particular conventional or physically drying) intaglio printing ink with which the document of value substrate is applied to one of its two main surfaces or to both Main surfaces are printed in the form of intaglio printing.

8. (Preferred embodiment) value document substrate according to one of clauses 1, 2, 3, 6 or 7, wherein the value document substrate is a value document, in particular a bank note or an identification document.

9. (Preferred embodiment) value document substrate according to one of clauses 1 to 8, the value document substrate being adapted so that the ink drying is accelerated after printing when exposed to UV radiation as a result of the photosensitizer to generate singlet oxygen. 10. (Preferred embodiment) value document substrate according to one of clauses 1 to 9, wherein the value document substrate is adapted so that the photosensitizer for generating singlet oxygen when exposed to UV radiation has an antimicrobial, in particular antibacterial and / or antiviral and / or antifungal effect unfolded, wherein the photosensitizer is preferably incorporated into the substrate surface, particularly preferably in an impregnation, in a precoating, in an ink acceptance layer or in a protective lacquer.

11. (Preferred embodiment) document of value substrate according to one of clauses 1 to 10, wherein the photosensitizer for generating singlet oxygen is a 1,7-diaryl-1,6-heptadiene-3,5-dione derivative, as described, for example, in of WO 2017/032892 Al.

12. (Preferred embodiment) Document of value substrate according to one of Clauses 1 to 10, the photosensitizer for generating singlet oxygen being a 10H-benzo [g] pteridine-2,4-dione derivative (see, for example, WO 2012/175730 A1, WO 2012 / 175706A1 and WO 2012/175729 A1), an 1H-phenalen-1-one derivative (see e.g. WO 2012/113860 A2), a perinaphthenone dye (see e.g. WO 2012 / 113860A2) or a phenalen-1-one derivative (see, for example, WO 2018/167264 A1).

13. (Preferred embodiment) document of value substrate according to one of clauses 1 to 12, wherein the substrate is a paper substrate, a polymer substrate or a hybrid substrate, wherein in the case of the hybrid substrate in particular a film composite substrate with a core based on paper and outer layers on the Based on polymers or foils (in particular in connection with a pre- existing ink acceptance layer) or a composite substrate with a core made of a plastic material and outer layers based on paper.

14. (Second aspect) A method for disinfecting a value document substrate, comprising the step of providing a value document substrate according to one of clauses 1 to 13 and the step of subjecting the value document substrate to UV radiation so that the photosensitizer can generate singlet oxygen during irradiation with UV radiation an antimicrobial, in particular antibacterial and / or antiviral and / or antimycotic, effect unfolds.

Detailed description of the invention Oxygen has two different excited states, both of which have a significantly higher energy than the ground state. In both states, the spins of the electrons are antiparal, contrary to Hund's rule. The more stable excited oxygen is also called singlet oxygen OO2) after the quantum mechanical term for this state. The two singlet states differ in whether the two electrons are in one (term symbol: ^a A _g ) or both n * orbitals (term symbol: ^a Z _g ). The ¹ Z _g state is energetically less favorable and changes very quickly to the ¹ A _g state. The ¹ Z _g state is diamagnetic, the energetically more stable one ^! However, the A _g state shows due to the existing orbital moment (the quantum number corresponding to the projection of the orbital angular momentum onto the core-core connecting axis - symbolized by S, P, D etc. - has the value ± 2 ^{in the!} A _{g state)} Paramagnetism of comparable strength to that of triplet oxygen. Singlet oxygen can be formed in various ways: both photochemically from triplet oxygen and chemically from other oxygen compounds. A direct extraction from triplet oxygen by irradiation with electromagnetic radiation (eg light) is, however, excluded for quantum mechanical reasons, in the form of the selection rules for the emission or absorption of electromagnetic radiation. One way of circumventing this prohibition is to simultaneously irradiate photons and collide two molecules. This unlikely process, which is more likely in the liquid phase, creates the blue color of liquid oxygen (absorption in the red spectral range). Singlet oxygen can also be represented photochemically with the help of suitable dyes such as methylene blue or eosin. It is obtained chemically from peroxides. When hydrogen peroxide is reacted with sodium hypochlorite, the unstable peroxohypochlorous acid is initially formed, which quickly breaks down into hydrogen chloride or chloride and singlet oxygen. Experimentally, chlorine can also be introduced into an alkaline hydrogen peroxide solution, which then initially creates hypochlorite, which then reacts further. The singlet oxygen reacts quickly with emissions in the red area at 633.4 nm and 703.2 nm to form triplet oxygen.

This form of oxygen is a powerful and selective oxidizing agent and is widely used in organic chemistry. In contrast to normal oxygen, it reacts with 1,3-dienes in a [4 + 2] cycloaddition to form peroxides. Singlet oxygen reacts with alkenes and alkynes in a [2 + 2] cycloaddition.

The present invention is based on the knowledge that singlet oxygen is able to remove unsaturated double bonds, as they are in conventional len binders for background colors or intaglio printing inks can be used to network via an alpha-H abstraction. If a printing ink suitable for printing a (paper) substrate is mixed with photosensitizer and exposed to UV radiation immediately after printing, the drying of the ink is accelerated.

If a certain compound, which is suitable as a photosensitizer for generating singlet oxygen, is added to a conventional printing ink, surprisingly even two advantageous properties can be implemented:

Firstly, the accelerated drying of conventional inks, especially a background color and / or an intaglio printing ink.

Second, an antimicrobial, in particular antibacterial and / or antiviral and / or antimycotic finish of a document of value such as a bank note.

Antimicrobial, for example antimycotic, coatings for surfaces are known in the prior art. According to the invention, an antimicrobial, for example antimycotic and / or antiviral and / or antibacterial, coating of a document of value substrate on the basis of a photo-induced generation of singlet oxygen by a photosensitizer is provided. When exposed to (UV) light, singlet oxygen is released which, due to its reactivity, is able to kill bacteria, viruses and / or fungi in the immediate vicinity. Due to the high diffusibility of oxygen, it is not necessary that the photosensitizer is applied in close proximity to the bacteria, viruses and / or fungi, but the photosensitizer also acts at a distance of approx. 5 mm. If the photosensitizer is used, for example, as a component of an undercoat or intaglio printing ink, a large area of a document of value such as a bank note can be given an antimicrobial, in particular antibacterial and / or antiviral and / or antimicotic finish. Furthermore, a subsequent overpainting can optionally take place, because singlet oxygen can also diffuse through a lacquer layer a few micrometers thick. The value document substrate according to the invention, for example a security paper or a bank note, has a flat substrate which is at least partially provided with an antimicrobial coating containing the photosensitizer for generating singlet oxygen. The antimicrobial coating extends the service life of documents of value that are produced with the security paper according to the invention and reduces the risk of illness in people through the transmission of pathogenic microorganisms when they come into contact with documents of value of this type. "Antimicrobial" in the context of the present invention means that there is an activity against microorganisms, the effect ideally being a killing of the microorganisms, but also being able to consist in an inhibition of the growth and multiplication of the microorganisms. The term “antimicrobial” means in particular “antiviral” and / or “antibacterial” and / or “antimycotic”.

"Microorganisms (microbes)" in the context of the invention are in particular bacteria, fungi, such as molds and yeasts, and viruses, with im The focus of the present invention are the potentially pathogenic microorganisms.

Agents for combating microorganisms, i.e. "antimicrobial agents" in the context of the invention therefore include in particular antibacterial, antifungal and antiviral agents, their action being both biocidal (for example bactericidal) and biostatic (for example bacteriostatic).

The antimicrobial coating containing the photosensitizer for generating singlet oxygen can be single-layer or multilayer. The antimicrobial coating can, for example, be formed in two layers, whereby it is primarily the upper layer, ie the outer layer, which contains the photosensitizer for generating singlet oxygen, while the lower layer, ie the layer between the substrate and the upper layer, primarily establishes contact with the substrate. The photosensitizer for generating singlet oxygen can furthermore be a component of a (pre) coating or an ink acceptance layer of the document of value substrate.

The coating or primer layer containing the photosensitizer for generating singlet oxygen can in particular be formed by a physically drying lacquer layer. “Physically drying” means that drying takes place by evaporation and / or absorption of the solvents or dispersants into the substrate. The production of suitable coatings is known to the person skilled in the art, see, for example, EP 2634309 A1 and WO 2004/072378 A1. Water-based dispersion paints are particularly preferred. Examples of suitable primer compositions are compositions based on acrylates, Polyester acrylates, urethane acrylates, polyester polyurethanes and acrylic styrene polyurethanes. Water-based dispersions, in particular water-based dispersions of aliphatic components, are particularly preferred.

It goes without saying that all coating compositions can contain the usual auxiliaries. Customary auxiliaries are, for example, coalescing agents, leveling agents, wetting agents, defoaming agents, viscosity modifiers, dispersing aids and diluents. Feature substances that are preferably not visually recognizable, such as, for example, luminescent substances, can also be contained in the compositions.

The photosensitizer contained in the respective coating or ink layer (e.g. a background print or intaglio printing) to generate singlet oxygen is effective even in small amounts, in terms of accelerating ink drying and the antimicrobial effect. The photosensitizer can be used, for example, in an amount of 0.05% by weight to 0.20% by weight of the composition (wet) which forms the respective layer.

If the photosensitizer is excited by means of a UV LED lamp instead of a mercury vapor lamp, the beneficial effects are achieved with a low use of energy.

A 1,7-diaryl-1,6-heptadiene-3,5-dione derivative is preferred as the photosensitizer. Suitable 1,7-diaryl-1,6-heptadiene-3,5-dione derivatives and their preparation are described in WO 2017/032892 A1.

Preferred structures of suitable photosensitizers are described below, see also WO 2017/032892 A1: l, 7-diaryl-l, 6-heptadiene-3,5-dione derivative of the formula (100): and / or at least one l, 7-diaryl-l, 6-heptadiene-3,5-dione derivative of the formula (101): or a salt and / or ester and / or complex thereof, where Q ³ , Q ^3a , Q ⁴ and Q ^{4a are} each independently a substituted or unsubstituted monocyclic or polycyclic, aromatic radical or a substituted or unsubstituted monocyclic or polycyclic, heteroaromatic Radical where K is hydrogen or a cation, and where M ^{z + is} a cation of a metal, where z is the formal oxidation number of the metal M and z is an integer from 1 to 7, preferably from 2 to 5, and whereby (Al) at least one of the radicals Q ³ , Q ^3a , Q ⁴ and Q ^43, each independently of one another, is an unsubstituted monocyclic or polycyclic, heteroaromatic radical which has at least five ring atoms, the ring atoms at least one carbon atom and at least one, preferably - wise protonatable, contain nitrogen atom, or

(a2) at least one of the residues Q ³ , Q ^3a , Q ⁴ and Q ^4a , preferably each of the residues Q ³ and Q ⁴ , preferably each of the residues Q ³ and Q ^3a , preferably each of the residues Q ³ , Q ^3a and Q ⁴ , preferably each of the radicals Q ³ , Q ^3a , Q ⁴ and Q ^4a , each independently of one another with at least one, preferably 1 to 9, more preferably 1 to 7, more preferably 1 to 5, more preferably 1 to 4, more preferably 2 to 3, organic radical (s) Wl, which has the general formula (4), (5), (6), (7), (8), or (9), preferably (5), (7), or (9), has:

- (C (D) (E)) _h -X, (4) -A- (C (D) (E)) hX, (5)

- (C (D) (E)) _k -aryl- (C (D) (E)) iX, (6)

-A- (C (D) (E)) _k -aryl- (C (D) (E)) iX, (7)

- ((C (D) (E)) mA) p- (C (D) (E)) _n -X, (8)

-A - ((C (D) (E)) _m -A) p- (C (D) (E)) _n -X, (9), is substituted, where h is an integer from 1 to 20, preferably from 2 to 8, where k is an integer from 0 to 10, preferably from 1 to 8, vorzugswei se from 2 to 6, where 1 is an integer from 0 to 10, preferably from 1 to 8, preferably from 2 to 6, and where m, n and p are each independently an integer from 1 to 6, preferably from 2 to 4, and where A is each independently oxygen or sulfur, preferably oxygen, where D and E are each independently hydrogen, halogen,

G-RW, or GC (= G) -R ⁽ⁿ⁾ , where G each independently of one another is oxygen or sulfur, preferably oxygen, and where the radicals RO and R ^{(u) are} each independently hydrogen, methyl, Means ethyl, n-propyl, n-butyl, n-pentyl, phenyl or benzyl, where phenyl and benzyl can be unsubstituted or substituted, where aryl means a substituted or unsubstituted aromatic or a substituted or unsubstituted heteroaromatic which does not contain a nitrogen atom , where X is in each case, independently of one another, an organic radical which (i) at least one neutral, protonatable nitrogen atom, or (ii) at least one positively charged, preferably quaternary, nitrogen atom or (iii) at least one positively charged, preferably quaternary, phosphorus atom contains, and wherein the radicals RI, R2, R3, R4 and R5 each independently of one another what hydrogen, halogen, alkyl with 1 to 12 carbon atoms, cycloalkyl with 1 to 12 carbon atoms, alkyl aryl with 1 to 12 carbon atoms, aryl with 5 to 20 carbon atoms, ether with 2 to 12 carbon atoms or glycol with 2 to 12 carbon atoms, or where (b) the radical R3 is an organic radical W2 , which has the general formula (4), (5),

(6), (7), (8), (9), or (10), preferably (4), has:

- (C (D) (E)) _h -X, (4)

-A- (C (D) (E)) _h -X, (5) - (C (D) (E)) _k -aryl- (C (D) (E)) iX, (6)

-A- (C (D) (E)) _k -aryl- (C (D) (E)) iX, (7) - [(C (D) (E)) _m -A] _p - (C ( D) (E)) _n -X, (8) -A - [(C (D) (E)) _m -A] _p - (C (D) (E)) nX, (9), - (- C (D) = C (E) -) _r -X, (10) and wherein, optionally, at least one of the residues Q ³ , Q ³³ , Q ⁴ and Q ⁴³ , vorzugwei se each of the residues Q ³ and Q ⁴ , preferably each of the residues Q ³ and Q ^3a , preferably each of the residues Q ³ , Q ^3a and Q ⁴ , preferably each of the radicals Q ³ , Q ^3a , Q ⁴ and Q ^4a , each independently of one another with at least one, preferably 1 to 9, more preferably 1 to 7, more preferably 1 to 5, further preferably 1 up to 4, more preferably 2 to 3, organic radical (s) Wl, which has the general formula (4), (5), (6), (7), (8), or (9), preferably (5), (7), or (9), is substituted, where h is an integer from 1 to 20, preferably from 2 to 8, where k is an integer from 0 to 10, preferably from 1 to 8, vorzugswei se from 2 to 6, where 1 is an integer from 0 to 10, preferably from 1 to 8, preferably from 2 to 6, and where m, n, p, and r are each independently an integer of 1 to 6, preferably from 2 to 4, and where A is each independently oxygen or sulfur, preferably oxygen, where D and E are each independently hydrogen, halogen, G-RW, or GC (= G) -R ⁽ⁿ⁾ , where G is each independently Sau - is material or sulfur, preferably oxygen, and where the residues RW and RW are each independently hydrogen, methyl, ethyl, n-propyl, n-butyl, n-pentyl, phenyl or benzyl, where phenyl and benzyl are unsubstituted or may be substituted, where aryl is a substituted or unsubstituted aromatic or a substituted or unsubstituted heteroaromatic which does not contain a nitrogen atom, where X is in each case, independently of one another, an organic radical which (i) at least one neutral, protonatable nitrogen atom, (ii) at least one positively charged, preferably quaternary, nitrogen atom or (iii) at least contains a positively charged, preferably quaternary, phosphorus atom, and where the radicals RI, R2, R4 and R5 are each independently hydrogen, halogen, alkyl with 1 to 12 carbon atoms, alkylaryl with 1 to 12 carbon atoms, aryl with 5 up to 20 carbon atoms, ethers with 2 to 12 carbon atoms or glycol with 2 to 12 carbon atoms.

According to further preferred embodiments, the photosensitizer for generating singlet oxygen can be a 10H-benzo [g] pteridine-2,4-dione derivative (see in particular WO 2012/175730 A1, WO 2012/175706 A1 and WO 2012/175729 A1 ), an 1H-phenalen-1-one derivative (see in particular WO 2012/113860 A2), a perinaphthenone dye (see in particular WO2012 / 113860 A2) or a phenalen-1-one derivative (see in particular WO 2018/167264 Al).

According to a preferred embodiment, the photosensitizer Be is part of a (in particular conventionally or physically drying) background paint. Printing a (paper) substrate with such a background color, followed by exposure to UV radiation, results in an advantageous, accelerated drying of the printed substrate.

According to a further preferred embodiment, the photosensitizer is part of a (in particular conventionally or physically drying) intaglio printing ink. Printing a (paper) substrate with such a intaglio printing ink, followed by exposure to UV radiation, results in an advantageous, accelerated drying of the printed substrate.

According to a further preferred embodiment, an activation of the antimicrobial, in particular antibacterial and / or antiviral len and / or antimycotic effect through UV irradiation in the circulation of documents of value, in particular in the circulation of the bank note.

In order to improve the oxidative drying of thicker layers of paint, for example engraving inks, in particular with a layer thickness> 3 μm, and printing inks with UV radiation-absorbing components, such as carbon black or titanium dioxide, it is optionally proposed that the respective printed substrate not only be on the with fresh printing ink applied substrate side, but also on the opposite side of the substrate through the substrate is exposed to UV radiation. Accordingly, the exposure to UV radiation takes place preferably on both sides of the substrate.

Suitable substrates are in particular paper substrates, polymer substrates and so-called hybrid substrates, which are to be understood as meaning film composite substrates which either have a core based on paper and outer layers based on polymers or else a core made of a plastic material and outer layers based on paper. It is preferred to use substrates based on cotton fibers, which may optionally contain mixed fibers and / or synthetic fibers. In addition, paper, or more precisely a paper-like substrate, can in a special case also consist exclusively of synthetic fibers.

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

In the case of a polymer substrate or a composite substrate with a core made of paper and outer layers based on polymers, it is expedient to apply one or more coatings to the polymeric material which ensure the adhesion of the print to be applied to the respective substrate. This applied to the polymeric material Layer is commonly referred to as an ink acceptance layer. In the case of a paper substrate, ink acceptance layers are generally unnecessary, but the paper substrate can be coated in whole or in part in order to provide it with certain properties, for example luminescent properties due to applied luminescent substances. Ink-accepting layers are usually based on fillers, such as titanium dioxide, aluminum oxide or silicon dioxide pigments, incorporated in a suitable binder.

The step of treating the printed value document substrate with UV radiation is expediently carried out by using UV drying systems, which can be based in particular on mercury UV medium pressure lamps or iron or gallium-doped mercury UV medium pressure lamps. The emitter power per lamp is in the range from 120 W / cm to 250 W / cm, preferably 180 W / cm. A suitable radiator system are, for example, the BLK-5 or BLK-2 units offered by IST METZ GmbH.

In the case of a (simultaneous) printing machine equipped with a UV drying system, the method is expediently carried out at a printing speed of 8,000 to 12,000 sheets / h, in particular 10,000 sheets / h, and an individual radiation dose rate setting within a range of 4 mj / cm ² up to 100 mj / cm ² . With regard to avoiding the shrinkage of the printed sheet, it is preferred to set the radiation output within a range of 4 mj / cm ² to 60 mj / cm ² , the range of 10 mj / cm ² to 40 mj / cm ^{2 being} particularly preferred will.

The step of drying the printed value document substrate treated with UV radiation takes place at room temperature or at elevated temperatures. temperature. Here, room temperature is understood to mean a temperature of 20 ° C. The drying at an elevated temperature can take place, in particular, at a temperature in a range from 35.degree. C. to 40.degree.

In order to avoid the shrinkage of the value document substrate, it is preferred to carry out the step of drying the value documents in the form of a value document stack. The value document stack can in particular have 200 to 10,000 printed sheets, preferably 5,000 to 7,000 printed sheets. A stack of documents of value with approximately 6000 printed sheets is particularly preferred for drying. Furthermore, it is preferred that the stack core temperature does not exceed a temperature of 40 ° C. The drying of the documents of value in the form of a stack of documents of value is preferably carried out at room temperature.

The simultaneously achieved technical effect of activating the antimicrobial len, in particular antibacterial and / or antiviral and / or antimycotic, effect by means of UV irradiation in the circulation of documents of value, in particular special in circulation of the banknote, is extremely advantageous.

According to a special variant, it is proposed that the coating, in particular the printing ink or the varnish, contain wavelength-sensitive photosensitizers that respond only to the wavelength of the UV radiator in the printing machine in order to prevent the oxidative drying of the oxidatively drying coating, in particular printing inks or varnishes (so-called oil printing varnishes) to accelerate. Furthermore, wavelength-sensitive photosensitizers can preferably be included, which are only matched to the wavelength and / or energy of the UV radiator for disinfecting the documents of value, in particular banknotes. Further exemplary embodiments and advantages of the invention are explained below in conjunction with the figures.

Show it:

1 shows a value document substrate according to the invention, in the present case a security paper suitable for the production of a bank note, according to a first exemplary embodiment; 2 shows a value document substrate according to the invention, in the present case a bank note, according to a second exemplary embodiment; and

3 shows a value document substrate according to the invention, in the present case a bank note, according to a third exemplary embodiment.

FIG. 1 shows a value document substrate 1 according to the invention, in the present case a security paper suitable for the production of a bank note, according to a first exemplary embodiment in a cross-sectional view. The value document substrate 1 is based on a paper substrate 2, which has a coating 3 or 4, namely a lacquer, which has a special photosensitizer for generating singlet oxygen, on both its upper and lower main surfaces. A 1,7-diaryl-1,6-heptadiene-3,5-dione derivative, which is described in WO 2017/032892 A1 (see in particular the structures (40) to (63), (68 ), (69a), (69b) and (70) in claim 14 of WO 2017/032892 A1).

To produce the security paper according to the invention, a full-area paper substrate 2 is provided and the antimicrobial coating is applied to it. layer applied by first in a first step as a lower coating layer a physically drying layer is applied to the substrate in order to establish contact with the underlying substrate and close its pores, and then in a second step as an upper coating layer a photosensitizer for Er generation of singlet oxygen having lacquer layer is applied.

The application can take place by customary printing processes, for example by flexographic printing. The lower coating layer is only optional, i.e. not absolutely necessary for carrying out the invention.

The security paper obtained showed in the course of exposure to UV radiation during the subsequent printing with conventional background color and with conventional intaglio printing ink as a result of the presence of the photosensitizer to generate singlet oxygen, a greatly accelerated ink drying. In the example, a simultaneous printing machine suitable for printing with conventionally drying printing inks with a retrofitted UV drying system from IST Metz ("BLK-5", two lamps per side with a lamp power of 180 W / cm each) was used.

In addition, soiled security paper samples were tested for their infecting and thus antibacterial effectiveness. It showed a high disinfecting and thus antibacterial effectiveness, which comes about in the course of exposure to UV radiation as a result of the generation of singlet oxygen.

FIG. 2 shows a value document substrate 5 according to the invention, in the present case a bank note, according to a second exemplary embodiment in FIG Cross-sectional view. The banknote 5 is based on a paper substrate 6 which is provided on both its upper and its lower main surface with a partial background print 7 in the form of a pattern, generated by printing technology. The background color is based on a conventional, physically drying background color, which has a special photosensitizer as a further component to generate singlet oxygen. A l, 7-diaryl-l, 6-heptadiene-3,5-dione derivative, which is described in WO 2017/032892 A1 (see in particular the structures (40) to (63), ( 68), (69a), (69b) and (70) in claim 14 of WO 2017/032892 A1).

The resulting banknote 5 showed in the course of exposure to UV radiation during the drying of the background color and during the subsequent printing with conventional intaglio printing ink in order to produce a pattern 8 in intaglio printing, due to the presence of the Photosensi bilizer to generate singlet oxygen in the Background printing layer 7 greatly accelerated ink drying. In the example, a simultaneous printing machine suitable for printing with conventionally drying printing inks with a retrofitted UV drying system from IST Metz ("BLK-5", two lamps per side with a lamp power of 180 W / cm each) was used.

In addition, soiled banknotes were tested for their disinfecting and thus antibacterial effectiveness. It showed a high level of infecting and thus antibacterial effectiveness, which comes about in the course of exposure to UV radiation as a result of the generation of singlet oxygen. FIG. 3 shows a value document substrate 9 according to the invention, in the present case a bank note, according to a second exemplary embodiment in a cross-sectional view. The bank note 9 is based on a paper substrate 10, which is provided with a partial background print 11 in the form of a pattern, produced by printing technology, on both its upper and its lower main surface. The background color is based on a conventional, physically drying background color. In a subsequent step, the banknote 9 was provided with an intaglio layer 12 by means of intaglio printing. The intaglio printing ink is based on a conventional, physically drying intaglio printing ink, which has as a further component a special photosensitizer for the generation of singlet oxygen. A 1,7-diaryl-1,6-heptadiene-3,5-dione derivative, which is described in WO 2017/032892 A1 (see in particular the structures (40) to (63), (68 ), (69a), (69b) and (70) in claim 14 of WO 2017/032892 A1).

The banknote 9 obtained showed, in the course of exposure to UV radiation during the drying of the intaglio printing layer 12, as a result of the presence of the photosensitizer for generating singlet oxygen, a greatly accelerated ink drying. In the example, a simultaneous printing machine suitable for printing with conventionally drying printing inks with a retrofitted UV drying system from IST Metz ("BLK-5", two lamps per side with a lamp power of 180 W / cm each) was used.

In addition, soiled banknotes were tested for their disinfecting and thus antibacterial effectiveness. It showed a high level of the infecting and thus antibacterial effectiveness, which in the course of the exposure hit with UV radiation as a result of the generation of singlet oxygen.

Claims

Patent claims

1. Document of value substrate with two opposing main surfaces, with at least one of the two main surfaces being a photosensitizer

Has generation of singlet oxygen.

2. The value document substrate according to claim 1, wherein both main surfaces of the value document substrate each have a photosensitizer for generating singlet oxygen.

3. Value document substrate according to claim 1 or 2, wherein the main surface of the value document substrate or both main surfaces of the value document substrate is each provided over the entire surface with the photosensitizer for generating singlet oxygen.

4. Value document substrate according to one of claims 1 to 3, wherein the photo sensitizer is introduced to generate singlet oxygen in a coating, preferably a lacquer.

5. Document of value substrate according to one of claims 1 to 4, wherein the document of value substrate is a security paper for the production of documents of value, in particular banknotes.

6. Value document substrate according to one of claims 1 to 3, wherein the photosensitizer for generating singlet oxygen is part of a background color Un with which the value document substrate is printed on one of its two main surfaces or on both main surfaces in the form of a background print.

7. The value document substrate according to one of claims 1 to 3, wherein the photo sensitizer for generating singlet oxygen is part of an intaglio printing ink with which the value document substrate is printed on one of its two main surfaces or on both main surfaces in the form of intaglio printing.

8. Value document substrate according to one of claims 1, 2, 3, 6 or 7, wherein the value document substrate is a value document, in particular a bank note or an identification document.

9. The value document substrate according to one of claims 1 to 8, wherein the value document substrate is adapted to the fact that the ink drying is accelerated after the printing upon exposure to UV radiation as a result of the photosensitizer to generate singlet oxygen.

10. Value document substrate according to one of claims 1 to 9, wherein the value document substrate is adapted so that the photosensitizer for generating singlet oxygen when exposed to UV radiation develops an antimicrobial, in particular antibacterial and / or antiviral and / or antimycotic effect, the photosensitizer is preferably incorporated in the substrate surface, particularly preferably in an impregnation, in a precoating, in an ink acceptance layer or in a protective lacquer.

11. Value document substrate according to one of claims 1 to 10, wherein the photosensitizer for generating singlet oxygen is a 1,7-diaryl-1,6-heptadiene-3,5-dione derivative.

12. Document substrate of value according to one of claims 1 to 10, wherein the photosensitizer for generating singlet oxygen is a 10H-benzo [g] pteridine-2,4-dione derivative, a 1H-phenalen-1-one derivative, a perinaphthenone Dye or a phenalen-l-one derivative.

13. Value document substrate according to one of claims 1 to 12, wherein the substrate is a paper substrate, a polymer substrate or a hybrid substrate, wherein in the case of the hybrid substrate in particular a film composite substrate with a core based on paper and outer layers based on polymers or films , in particular in connection with an ink-accepting layer present on the respective polymer or the respective film, or a composite substrate with a core made of a plastic material and outer layers based on paper is present.

14. A method for disinfecting a value document substrate, comprising the step of providing a value document substrate according to one of claims 1 to 13 and the step of exposing the value document substrate to UV radiation, so that the photosensitizer is used to generate singlet oxygen when irradiated with UV radiation an antimicrobial, in particular antibacterial and / or antiviral and / or antimycotic, effect unfolds.