WO2023281365A1

WO2023281365A1 - Antibacterial and antiviral treatment for coins, banknotes and tokens

Info

Publication number: WO2023281365A1
Application number: PCT/IB2022/056109
Authority: WO
Inventors: Luigino Gravelli
Original assignee: L & G Holding S.R.L.
Priority date: 2021-07-07
Filing date: 2022-06-30
Publication date: 2023-01-12
Also published as: IT202100017894A1

Abstract

The present patent application relates to an antibacterial solution used in an antibacterial and antiviral treatment for coins, banknotes, tokens, and more generally for paper currency.

Description

ANTIBACTERIAL AND ANTIVIRAL TREATMENT FOR COINS, BANKNOTES AND TOKENS

Technical field of the invention

The present invention finds application in the field of coins, banknotes and tokens.

Background art

In this particular historical moment, the advent of COVID 19 has stimulated the development of means for cleaning, sanitizing and disinfecting surfaces and objects so as to make them uncontaminated by bacterial and viral loads. In the case in point, banknotes and coins were found to be a means of transmitting the SARS-Cov-2 virus (COVID- 19) because, given the porous nature of the substrate, through studies conducted, survival has been verified up to 28 days on surfaces such as banknotes and 3-4 days on metal and plastic, or on coins and tokens. Therefore, the use of banknotes, coins and tokens poses a serious risk to the transmission of the virus among the population. It can be assumed how the virus can be transmitted from person to person in a very short time with the circulation of banknotes, coins and tokens in a single day. Virus resistance in the environment is relatively low, although some viruses (e.g., some respiratory viruses such as coronaviruses) can survive longer, as a function of local environmental conditions and the type of substrate on which they are deposited. The analysis of 22 studies reveals that human coronaviruses such as severe acute respiratory syndrome coronavirus (SARS), Middle East respiratory syndrome coronavirus (MERS) or endemic human coronavirus (HCoV) can persist on inanimate surfaces such as paper, fabric, metal, glass or plastic for up to 9 days, but can be efficiently inactivated by surface disinfection procedures with specific products. According to a study conducted by the University of Oxford, a European banknote contains an average of 26,000 bacteria belonging to different species, some of which are pathogenic. The most contaminated currency is the Danish krone (40,200 bacteria), followed by the Swiss franc (32,400 bacteria). The paper of euros is instead the cleanest, with 11,000 microorganisms on average. This figure is from 2014, well before the advent of COVID 19. In more recent research dated 2020, researchers at New York University analyzed the presence of microorganisms on dollar bills. The study is part of the "Dirty Money" project, which aims to reconstruct citizens' state of health by analyzing the variety of bacteria from the DNA of microbes on the money in circulation, sequencing the DNA present. Researchers have thus been able to identify a great diversity of bacteria on paper money, most of them relatively harmless to people, but some potentially dangerous. In total, more than 3,000 types of bacteria have been identified, including some drug-resistant species; only about 20% of the bacterial DNA has been found to belong to known species, while the rest are microbiological loads which have not yet been classified. The most abundant species identified on paper money are the bacteria which cause acne, followed by the bacterial flora normally present on skin. But the presence of pathogenic staphylococcus species and bacteria associated with gastric ulcers, pneumonia and food poisoning has also been found. From the moment in which thousands of bacteria, fungi and pathogens nest on a banknote, it is understood that it can cause diseases such as skin infections, stomach ulcers, food poisoning, etc.

The patent application EP 2,491,956 describes a method for inactivating viruses comprising the step of irradiating a photocatalytic material with which the viruses are in contact, wherein such a material comprises a glass substrate with a titanium oxide coating.

The patent application JP 2017149860 describes a basic solution, by the addition of ammonia, comprising two transition metals and titanium oxide.

The patent application WO 2010/028016 describes a method for preparing a titania dispersion by mixing two different dispersions synthesized by a solvothermal and hydrolysis process.

The patent application WO 2014/141812 describes a basic dispersion (pH 7.0-9.0) of titanium oxide for obtaining an antibacterial and antiviral coating. The patent application US 2014/083473 speculates the possibility of including a self-cleaning feature in a substrate material or providing said substrate with a self cleaning coating or with an ink; although banknotes are mentioned among the substrates, the method described, which is not accompanied by any details about the preparation of such a coating, is particularly dedicated to a polymeric substrate represented by bioriented oriented polypropylene (BOPP).

Summary of the invention

The inventors of the present patent application have surprisingly found that the above problems can be solved by the solution of the present invention, which provides permanent products, i.e., which last over time once applied to a substrate, capable of eliminating said microorganisms such as bacteria and viruses, with functional chemical additives, capable of being activated also with a photochemical action, suitable for food contact, as well as the methods for obtaining them.

Object of the invention

In a first object, the present invention describes a solution for the antibacterial and antiviral treatment of coins, banknotes, tokens and the like.

In a second object, there is described a method for preparing the antibacterial and antiviral solution of the invention. In a third object, there is described a method for the antibacterial and antiviral treatment of coins, banknotes, tokens and the like.

Coins, banknotes, tokens and the like treated according to the invention are further objects of the present patent application.

Brief description of the drawings

Figure 1 shows the industrial system for preparing the solutions of the present invention;

Figure 2 shows a system for applying the solutions of the present invention to banknotes with flexographic printing;

Figure 3 shows a system for applying the solutions of the present invention to coins and tokens;

Figure 4 shows a graph with the results of the photocatalytic activity tests;

Figure 5 shows the results obtained from analyses on viral strains of SARS-Cov-2 according to ISO 18184:2019. Detailed description of the invention

According to a first object of the invention, a solution with antibacterial and antiviral activity is described.

For the purposes of the present invention, the term "antibacterial activity" means the property of a solution according to the present invention to be effective against a broad spectrum of bacteria; such an activity is tested in UNI ISO analyses with Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive).

For the purposes of the present invention, the term

"antimicrobial activity" means the property of a solution according to the present invention to be effective against bacteria, mold and fungi and to continuously inhibit the growth of microorganisms on surfaces for very long periods of time.

For the purposes of the present invention, the term

"antiviral activity" means the property of a solution according to the present invention to be effective against viruses, such as COVID-19 and H1N1 (Influenza A), determined by a test according to ISO regulations.

For the purposes of the present invention, the described solution is a colloidal solution.

For the purposes of the present invention, the colloidal solution comprises titanium dioxide and one or more additives in mixture.

The solution of the invention can be an aqueous colloidal solution or an alcoholic solution, in particular ethanol-based .

Alternatively, the colloidal solution of the invention can be a water/alcohol solution.

For the purposes of the present invention, the titanium dioxide is amorphous photocatalytic titanium dioxide.

In particular, the titanium dioxide can be: of the Anatase type of the Rutile type of the Brookite type.

More in particular, the titanium dioxide is included in the colloidal solution of the invention in an amount of about 0.01-30% (w/w).

Preferably, the titanium dioxide is included in the colloidal solution of the invention in an amount of about 0.5%-3% (w/w), preferably about 0.9-1.2 (w/w) and more preferably about 0.99% (w/w).

For the purposes of the present invention, the water is preferably osmotic water or distilled water or purified water.

For the purposes of the present invention, the additives can be selected from the group comprising: silver; alternatively, the silver can for example be in the form selected from: silver chloride, silver nitrate, silver acetate, silver phosphate glass (or silver boron phosphate glass or silver phosphate glass), silver zeolite, silver copper zeolite, silver sodium hydrogen zirconium phosphate, silver zinc zeolite; copper; alternatively, the copper can be for example in the form selected from: Bis(l-hydroxy-lH-pyridine-2- thionate-O,S)copper (copper pyrithione), Bis(N-cyclohexyl- diazenium-dioxy)-copper, copper hydroxide, copper oxide (I), copper oxide (II), copper sulfate pentahydrate, copper thiocyanate, copper carbonate (II)-copper hydroxide (II)

(1:1), powdered copper, granular copper. calcium; the calcium can for example be in the form selected from: calcium oxide, calcium and magnesium oxide, calcium hydroxide, calcium dihydroxide, caustic lime, hydrated lime, slated lime, lime, burnt lime, dolomitic lime, Quicklime.

Other additives can be: Bronopol, salicylic acid, zinc, zinc pyrithione, calcium and magnesium oxide, chlorine dioxide (e.g., generated by acidification of sodium chlorite).

For the purposes of the present invention, a preferred additive is silver, added in the form of silver chloride, silver acetate or silver phosphate glass.

In a preferred aspect of the present invention, silver is added so that it is present at a concentration of 0.01 mg/1- 20 g/1 and preferably about 100 mg/1.

In a preferred aspect of the invention, the described colloidal solution has an acidic pH which is preferably about 2.0.

According to a second object, a process for preparing the colloidal solution of the invention is described.

In particular, such a process comprises the steps of:

I) adding water to amorphous photocatalytic titanium dioxide or to an alcoholic solution of amorphous photocatalytic titanium dioxide, II) adding one or more additives to the solution obtained from step I).

According to an aspect of the present invention, in step I) the titanium dioxide is included in the aqueous solution or in the alcoholic solution in an amount of about 0.5%-3%, preferably about 0.9-1.2 (w/w) and more preferably about 0.99% (w/w).

In particular, the alcoholic solution of titanium dioxide is a 1-99% v/v aqueous solution of ethanol having an alcoholic concentration of 60-99.9% v/v.

With respect to step II), the additives can be added in an amount by weight of about 0.0001-5%.

As regards certain specific additives, these are preferably in the following amounts:

- 0.5% silver on phosphate glass and/or

- 0.1% silver chloride and/or

- 0.001% silver acetate.

To obtain a homogeneous preparation, after the addition of step II), there proceeds with the emulsification by mechanical stirring at about 11,500 RPM for about 30 minutes .

For the purposes of the present invention, the preparation of the described colloidal solution is carried out at room temperature. For the industrial production of the solutions of the invention, a system such as that shown in Figure 1 can be used.

For the preparations of the amorphous photocatalytic solutions of the invention, it is possible to use an industrial system completely in SS316L stainless steel, explosion-proof, consisting of a hermetically closed container 101, capable of containing 150 liters of solution.

Through the tank 102, titanium dioxide is introduced by gravity. All the ingredients are previously weighed and prepared, as indicated in the preparations of the photocatalytic solutions described above.

The stirring motor 103 is started, it is a 2.2 kW power homogenizer, which rotates at 2,800 RPM. The titanium dioxide is inserted from the tank 104 and homogenized for 30 minutes. From the previously emptied tank 102, the additives are introduced and stirred for another 30 minutes. The solutions are made and, through the pump 105, by opening the three-way valve 106 it is transferred into the drums through the outlet 107.

According to a third object of the invention, a method for antibacterial and antiviral treatment of a substrate is described.

In particular, said substrate is a substrate intended to be touched by many people and has little chance of being washed or disinfected. Such a substrate can thus be made of paper or paper like material, metal (or metal-alloy) or plastic.

In a preferred aspect, such a substrate is money or equivalent means of payment and stamps.

According to a first aspect, such a substrate is therefore: banknotes, checks, stamps, tags, revenue seals, meal vouchers.

The banknotes, for example, consist of sheets of at least 80% cotton fiber and, in an aspect of the present invention, 100% cotton fiber.

Other similar substrates are: watermarked paper, certificates, diplomas, paper for personal documents (identity card, driver's license, passport, visas), tickets for events (concerts, shows, exhibitions).

Similar substrates can be voting cards.

According to another aspect of the invention, the money can be coins or in the form of tokens.

According to a further aspect, the substrate can be identification cards (badges), personal identity documents, driver's license, credit cards, bank cards, plastic cards (even of the magnetic type).

For the purposes of the present invention, the application of the colloidal solution of the invention to the substrate described can be conducted by appropriate techniques, selected for example from: spray application, flexographic printing, immersion. In particular, the application on "paper" substrates is preferably carried out by spray application or by flexographic printing, while the application on metal or plastic substrates is preferably carried out by spraying.

In particular, a solution of the invention can be applied in an amount of about 1 g/m², 2 g/m², 3 g/m², 4 g/m²,

5 g/m², 6 g/m², 7 g/m², 8 g/m², 9 g/m², 10 g/m², 11 g/m², 12 g/m², 13 g/m², 14 g/m², 15 g/m², 16 g/m², 17 g/m², 18 g/m², 19 g/m² and 20 g/m².

In an aspect of the invention, a solution as described above is applied in an amount of about 5-15 g/m², preferably

6 g/m²,

After application, a drying step can be included, at room temperature or by heating, for example with hot air jets, flame systems or resistance systems.

For example, the application with flexographic printing on banknotes can be carried out by means of the system shown in Figure 2.

The banknotes are coated after being printed.

A further printing module 200 is included consisting of an anilox printing cylinder 201 which, partially immersed in the tank 202, transfers the antibacterial and antiviral solution to the printing plate 203. A counterpressure cylinder 204 allows generating a pressure such as to allow the solution to be applied to the printing sheet 210. A doctor blade 205 is installed on the rear side of the anilox printing cylinder 201, which serves to remove and/or clean the excess solution after the deposit on the printing sheet 210.

The anilox rollers 201 are made of ceramic and/or Teflon, and/or polymer and/or other materials, are engraved with different methodologies and the print quality is defined by lines/cm. The larger the lines/cm, the smaller the amount of solution cm³/m² transferred to the printing sheet 210, or the smaller the lines/cm, the greater the amount of solution cm³/m² transferred to the printing sheet 210.

Therefore, anilox rollers 201 will be used, which through the printing plate 203 will be capable of transferring the solution to the printing sheet 210 from 0.1 cm³/m² to 30 cm³/m², preferably anilox rollers 201 will be used which will be able to transfer from 5 cm³/m² to 8 cm3/m² to the printing sheet 210, through the printing plate 203. The movement directions of the printing sheet 210 are indicated by arrows 250.

The movement directions of the cylinders 201,203 and 204 are indicated by arrows 252.

The printing sheet 210 must be printed on both sides, i.e., both the front side 211 and the rear side 212.

It is possible to insert a machine 300 which turns the already-printed printing sheet 210 from the front side 211 and uses a further printing module 200 to print on the back side 212, or can be overturned manually. The arrows 301 indicate that the printing sheet 210 has been overturned by the machine 300.

The printing module 200 can be single sheet 210, and/or multiple sheet 220, and/or reel 230, and all 210, 220, and

230 with both manual and automatic operation.

As regards the application of a solution according to the invention to coins or tokens, a system such as that shown in Figure 3 can be used.

To apply the solution of the invention, the coins and tokens 400 are inserted in a containment hopper 410, which automatically, through photocell 420, feeds a vibrating system also with a screw conveyor 411, to then be neatly arranged on a conveyor belt 412. The coins and tokens 400 enter the machine 450 which is provided with one or more nozzles 460 for spraying the solution directly onto the upper side 401 of said coins and tokens 400. The nozzle(s) 460 can be fixed or can be self-propelled or move horizontally with respect to the vertical feed direction of the conveyor belt 412. The arrows 430 indicate the movement direction of the coins and tokens 400. Once the coins and tokens 400 have exited the machine 450, they are overturned on the side opposite to 401, i.e., where the solutions have not yet been applied 402. A further machine 450 always provided with one or more nozzles 460, applies the solution on the opposite side 402. Hot air jets and/or flame systems and/or resistance systems 470 dry the coins or tokens 400.

An alternative to the machine 450 is the machine 490, consisting primarily of a stainless steel rotating drum 491. Inside said drum, one or more nozzles 460 are inserted to spray the solution directly onto said coins and tokens. The nozzles 460 are preferably fixed 461. The cylinder 491 is provided with specific grooves 492 therein for turning the coins or tokens 400 and at the same time mixing the solution directly on said coins and tokens 400 for better application. At the end of this operation, it is advisable to use hot air jets and/or flame systems and/or resistance systems 470 to dry the coins or tokens 400.

According to an alternative aspect of the present invention, the described colloidal solution can be applied before printing or after printing the substrate, for example by treating the paper or plastic material before making the final banknote or the card.

A substrate described above treated according to the invention represents a further object of the present patent application.

In particular, such a substrate is a substrate intended to be touched by many people and has little chance of being washed or disinfected.

Such a substrate can thus be made of paper or paper like material, metal (or metal-alloy) or plastic. In a preferred aspect, such a substrate is money or an equivalent means of payment and stamps.

According to a first aspect, such a substrate is therefore represented by: banknotes, checks, stamps, tags, revenue seals, meal vouchers.

Similar substrates can be voting cards.

According to a further aspect, the substrate can be represented by identification cards (badges), personal identity documents, driver's license, credit cards, bank cards, plastic cards (even of the magnetic type).

The invention will now be described by one or more examples of non-limiting embodiments.

EXAMPLE 1

Preparation of 1 liter of solution:

Alcoholic Base Using a percentage of additives preferably of 5 g per 1 liter of solution to be made, 474 ml of purified water are added to a beaker to which is added an amount of silver on phosphate glass (CAS 308069-39-8) having a density of 2.4 g/cm³, average particle size from 5 pm to 50 pm, in which the percentage of Ag alone is about 2%. The prepared ingredients are dispersed in the beaker with the H2O on a magnetic stirrer at about 6,000 RPM, the operation lasts about 20 minutes. The mixture is then homogenized at 12,000- 15,000 RPM with a shear emulsifier for about 20 minutes. A still further processing consists in sonicating the previously obtained compound using a 600 Watt Misonix 3000 for 10 minutes. If solutions of larger amounts are to be made, the sonicator is provided with Flocells™, capable of continuously processing up to 20 1/min of solution.

The obtained mixture is placed in a 1-liter separating funnel, dripped by gravity slowly, in a funnel provided with a paper filter for 1300/80 separations. The filtrate is collected in a flask. If the solutions to be filtered are too dense and/or concentrated for a filtration by gravity, it is possible to intervene using a vacuum filtration and/or under reduced pressure. In this case the flask for filtering has a side tail open on the top side which, through a rigid tube, can be connected to a vacuum pump. A neoprene gasket rests on the top of the flask, and a Buchner funnel must be placed the bottom of which is covered with filter paper for 1300/80 separations. When the vacuum pump is operated, the solution is sucked, precipitated on the bottom of the flask and separated from the solid material. To remove impurities from the solution, and not clog the system, Celite® 545 can be used, which has average particle size from 0.02 mm to 0.1 mm. Therefore, the pores of the paper are not clogged, and the freer holes allow the finest particles to pass unhindered. From the solution obtained, the amount of Ag is measured through atomic absorption, which must be between 0.01 mg/1 and 20 g/1, preferably 100 mg/1. The additive solution is prepared.

In another beaker, we added 414 ml of 96% ethanol CAS 64-17- 5 and put it under magnetic stirring at 6,000 RPM.

In a 1-liter separating funnel, we slowly dripped 112 ml of a photocatalytic titanium dioxide (TiCk) solution the active ingredient Ti content of which, determined by atomic absorption according to EPA 6010D:2018, is 4,499 mg/Kg and stirred for 30 minutes.

Subsequently, again in the same 1-liter separating funnel, we slowly dripped 474 ml of previously prepared additive containing 100 mg/kg of Ag and stirred for 30 minutes. After the magnetic stirring, the mixture is emulsified at 11,500 RPM for 30 minutes. A first solution of the invention is thus obtained.

EXAMPLE 2 Preparation of 1 liter of solution:

Aqueous Base

Using a percentage of additives preferably of 5 g per 1 liter of solution to be made, 474 ml of purified water are added to a beaker to which is added an amount of silver on phosphate glass (CAS 308069-39-8) having a density of 2.4 g/cm³, average particle size from 5 pm to 50 pm, in which the percentage of Ag is about 2%. The prepared ingredients are dispersed in the beaker with the H2O on a magnetic stirrer at about 6,000 RPM, the operation lasts about 20 minutes. The mixture is then homogenized at 12,000-15,000 RPM with a shear emulsifier for about 20 minutes. A still further processing consists in sonicating the previously obtained compound using a 600 Watt Misonix 3000 for 10 minutes. If solutions of larger amounts are to be made, the sonicator is provided with Flocells™, capable of continuously processing up to 20 1/min of solution.

The obtained mixture is placed in a 1-liter separating funnel, dripped by gravity slowly, in a funnel provided with a paper filter for 1300/80 separations. The filtrate is collected in a flask. If the solutions to be filtered are too dense and/or concentrated for a filtration by gravity, it is possible to intervene using a vacuum filtration and/or under reduced pressure. In this case the flask for filtering has a side tail open on the top side which, through a rigid tube, can be connected to a vacuum pump. A neoprene gasket rests on the top of the flask, and a Buchner funnel must be placed the bottom of which is covered with filter paper for 1300/80 separations. When the vacuum pump is operated, the solution is sucked, precipitated on the bottom of the flask and separated from the solid material. To remove impurities from the solution, and not clog the system, Celite® 545 can be used, which has average particle size from 0.02 mm to 0.1 mm. Therefore, the pores of the paper are not clogged, and the freer holes allow the finest particles to pass unhindered. From the solution obtained, the amount of Ag is measured through atomic absorption, which must be between 0.01 mg/1 and 20 g/1, preferably 100 mg/1. The additive is prepared.

In a second beaker, we added 414 ml of purified water CAS 7732-18-5 and put it under magnetic stirring at 6,000 RPM. In a 1-liter separating funnel, we slowly dripped, always in the second beaker, 112 ml of a photocatalytic titanium dioxide (TiCk) solution the active ingredient Ti content of which, determined by atomic absorption according to EPA 6010D:2018, is 4,499 mg/Kg and stirred for 30 minutes. Subsequently, again in the same 1-liter separating funnel, we slowly dripped 474 ml of previously prepared additive containing 100 mg/kg of Ag and stirred for 30 minutes. After the magnetic stirring, the mixture is emulsified at 11,500 RPM for 30 minutes. A second solution according to the invention is thus prepared. EXAMPLE 3

Preparation of 1 liter of solution:

Aqueous Base

Using a percentage of additives preferably of 0.01 g per 1 liter of solution to be made, 474 ml of purified water is added to a beaker to which is added an amount of 99.99% silver acetate (CAS 563-63-3) having a density of 166.91 g/mol, traces of heavy metals present <150 PPM, in powder. The prepared ingredients are dispersed in the beaker with the H2O on a magnetic stirrer at about 6,000 RPM, the operation lasts about 60 minutes. The mixture is then homogenized at 12,000-15,000 RPM with a shear emulsifier for about 30 minutes. A still further processing consists in sonicating the previously obtained compound using a 600 Watt Misonix 3000 for 10 minutes. If solutions of larger amounts are to be made, the sonicator is provided with Flocells™, capable of continuously processing up to 20 1/min of solution .

The obtained mixture is placed in a 1-liter separating funnel, dripped by gravity slowly, in a funnel provided with a paper filter for 1300/80 separations. The filtrate is collected in a flask. If the solutions to be filtered are too dense and/or concentrated for a filtration by gravity, it is possible to intervene using a vacuum filtration and/or under reduced pressure. In this case the flask for filtering has a side tail open on the top side which, through a rigid tube, can be connected to a vacuum pump. A neoprene gasket rests on the top of the flask, and a Buchner funnel must be placed the bottom of which is covered with filter paper for 1300/80 separations. When the vacuum pump is operated, the solution is sucked, precipitated on the bottom of the flask and separated from the solid material. To remove impurities from the solution, and not clog the system, Celite® 545 can be used, which has average particle size from 0.02 mm to 0.1 mm. Therefore, the pores of the paper are not clogged, and the freer holes allow the finest particles to pass unhindered. From the solution obtained, the amount of Ag is measured through atomic absorption, which must be between 0.01 mg/1 and 20 g/1, preferably 10 mg/1. The additive is prepared.

In a second beaker, we added 414 ml of purified water CAS 7732-18-5 and put it under magnetic stirring at 6,000 RPM. In a 1-liter separating funnel, we slowly dripped, always in the second beaker, 112 ml of a photocatalytic titanium dioxide (TiCk) solution the active ingredient Ti content of which, determined by atomic absorption according to EPA 6010D:2018, is 4,499 mg/Kg and stirred for 30 minutes. Subsequently, again in the same 1-liter separating funnel, we slowly dripped 474 ml of previously prepared additive containing 10 mg/kg of Ag and stirred for 30 minutes. After the magnetic stirring, the mixture is emulsified at 11,500 RPM for 30 minutes. A third solution according to the invention is thus prepared.

EXAMPLE 4

Preparation of 1 liter of solution:

Aqueous Base

Using a percentage of additives preferably of 1 g per 1 liter of solution to be made, 474 ml of an aqueous solution of halide anions is added to a beaker, to which is added an amount of 99.998% Silver Chloride (CAS 7783-90-6) having a density of 143.32 g/mol, traces of heavy metals present <25 PPM, in powder. The prepared ingredients are dispersed in the beaker with the H2O on a magnetic stirrer at about 6,000 RPM, the operation lasts about 60 minutes. The mixture is then homogenized at 12,000-15,000 RPM with a shear emulsifier for about 30 minutes. A still further processing consists in sonicating the previously obtained compound using a 600 Watt Misonix 3000 for 10 minutes. If solutions of larger amounts are to be made, the sonicator is provided with Flocells™, capable of continuously processing up to 20 1/min of solution.

In a second beaker, we added 414 ml of purified water CAS 7732-18-5 and put it under magnetic stirring at 6,000 RPM. In a 1-liter separating funnel, we slowly dripped, always in the second beaker, 112 ml of a photocatalytic titanium dioxide (TiCk) solution the active ingredient Ti content of which, determined by atomic absorption according to EPA 6010D:2018, is 4,499 mg/Kg and stirred for 30 minutes. Subsequently, again in the same 1-liter separating funnel, we slowly dripped 474 ml of previously prepared additive containing 100 mg/kg of Ag and stirred for 30 minutes. After the magnetic stirring, the mixture is emulsified at 11,500

RPM for 30 minutes. A fourth solution according to the invention is thus prepared.

EXAMPLE 5

Chromatic results

Solutions obtained according to Examples 1 to 4 were applied to €20 banknotes through an HVLP system, with a 0.3 mm nozzle, airless model Sata 4400 B. They were applied according to different concentrations.

Sample preparation

The banknotes were shielded with a non-absorbent sheet on 50% of the surface, so as to be able to verify the chromatic impact of the solutions and establish any color variations.

We applied the solutions on the banknotes with the following amounts: 1 g/m², 2 g/m², 3 g/m², 4 g/m², 5 g/m², 6 g/m², 7 g/m², 8 g/m², 9 g/m², 10 g/m², 11 g/m², 12 g/m², 13 g/m², 14 g/m², 15 g/m², 16 g/m², 17 g/m², 18 g/m², 19 g/m² and 20 g/m². Colorimetric variation results:

Banknotes coated with the solution of Example 1 Banknotes from 1 g/m² to 7 g/m² = Imperceptible;

Banknotes from 8 g/m² to 12 g/m² = Barely perceptible;

Banknotes from 13 g/m² to 17 g/m² = Perceptible;

Banknotes from 18 g/m² to 20 g/m² = Strong.

Banknotes coated with the solution of Example 2 Banknotes from 1 g/m² to 8 g/m² = Imperceptible;

Banknotes from 9 g/m² to 13 g/m² Barely perceptible; Banknotes from 14 g/m² to 17 g/m² = Perceptible;

Banknotes from 18 g/m² to 20 g/m² = Strong.

Banknotes coated with the solution of Example 3

Banknotes from 1 g/m² to 8 g/m² Imperceptible;

Banknotes from 9 g/m² to 12 g/m² Barely perceptible;

Banknotes from 13 g/m² to 17 g/m² = Perceptible;

Banknotes from 18 g/m² to 20 g/m² = Strong.

Banknotes coated with the solution of Example 4

Banknotes from 1 g/m² to 6 g/m² Imperceptible;

Banknotes from 7 g/m² to 12 g/m² = Barely perceptible; Banknotes from 13 g/m² to 15 g/m² = Perceptible;

Banknotes from 16 g/m² to 20 g/m² = Strong.

EXAMPLE 6

A) Photocatalytic analysis

To analyze the amorphous colloidal titanium dioxide-based photocatalytic solutions obtained according to Examples 1 to 4, a laser-beam UV-Vis spectroscope was used to measure the photocatalytic activity through absorbance changes resulting from the decomposition of pollutants (organic pigments) by a photocatalyst. It basically consists of a unit (sensor unit) comprising: two lamps, one for UV (black light) and one for the visible spectrum, an emitter element and a light receiver element. The incident light beam is characterized by the wavelength related to the absorbance of Methylene Blue, 660 nm. The intensity of each light signal reaching the receiver proportionally corresponds to an electrical signal whereby, defining the transmittance T as the fraction of incident light which is transmitted by a material, the instrument will detect such an amount with %T = (Vn- V0)/ (V100-V0) x 100 in which the denominator shows the electrical signal related to the incident light beam (acquired by the receiver, placing a completely reflective surface) while the numerator contains the electrical signal related to the transmitted light beam after a time n. As noted in the formula, both electrical signals are subtracted from the term VO related to that portion of light which does not reach the receiver (obtained by laying the sensor on one side so that the receiver can acquire only an infinitesimal fraction of the transmitted beam). What has been said so far can also be clearly extended to absorbance, which is defined as the decimal logarithm of the reciprocal of the transmittance: A = Iogl0(l/T). Consequently, the instrument output can be expressed in terms of Transmittance (%T), Absorbance (ABS) and/or Voltage (V). The instrument is calibrated before each analysis. The instrument is further provided with two independent channels, CHI and CH2, which allow performing measurements simultaneously on portions of a substrate treated and not treated with titanium dioxide. Four comparative analyses were performed each on a different substrate, comparing each photocatalytic solution with an uncoated portion that we will call As Such.

Sample preparation The substrates were coated by spray coating with the titanium dioxide solutions as reported in Examples 1 to 4, spraying an amount of 10 ml/m² respectively, with an HVLP system, with a 0.3 mm nozzle, airless model Sata 4400 B on the surface to be analyzed.

Results :

The graph of Figure 4 shows that the best photocatalytic activity in terms of the decomposition rate of the organic compounds deposited on the surface, after 60 minutes, and with the same amounts applied on the substrate, is that of the solution of Example 1, attesting the absorbance (ABS) at -0.019321 . b) Overall migration analysis in aqueous food simulant by total immersion

To carry out this food conformity analysis, according to EN 11861:2002 and EN 11863:2002, as established by Italian Ministerial Decree 72 dd. 9 May 2019, which updates Italian Ministerial Decree dd. 21 March 1973, Reg. 1935/2004.

Sample preparation

The substrates were spray coated with the solution of Example 1 by spraying an amount of 5 ml/m² with an HVLP system, with 0.3 mm nozzle, airless model Sata 4400 B on the surface to be analyzed. The samples are 5 x 5 cm stainless steel plates, as established by the regulation. The simulant used for the test, as established by the regulation, is 3% acetic acid (w/v). Test temperature: 40°C, exposure days: 10 days The laboratory test is repeated 3 times, both on samples treated with (10) and on samples as such (untreated).

Results :

The result obtained in all 6 cases analyzed is: NQ (NQ = not quantifiable, indicates a value lower than LoQ).

Therefore, the product is compliant to come into contact with food substances.

Regulatory references: Italian Ministerial Decree 72 dd. 9 May 2019 which updates Italian Ministerial Decree dd. 21 March 1973, Reg. 1935/2004.

The calculations were performed assuming that 1 kg of food comes into contact with 6 dm² of product.

C) Analysis with Bioluminometer

Bioluminometers are capable of detecting in a few seconds the presence of ATP (adenosine triphosphate), a molecule present in all animal, plant, bacterial cells, in yeast and molds.

It is a portable instrument which, combined with Lucipac A3 Surface swabs, detects contamination from ATP+AMP+ADP in real time, linked to bacterial and organic contamination, and thus to the degree of cleaning of the surfaces.

Fast and precise, the test can be used to control sanitation in all areas, for example healthcare, HO.RE.CA, industrial, public offices, etc., and to check any kind of substrate. Six €50 banknotes were withdrawn from an ATM and inserted into a wallet.

Sample preparation

The next day three banknotes were coated with 5 g/m² of the solution of EXAMPLE 2 with an HVLP system, with a 0.3 mm nozzle, airless model Sata 4400 B.

All the banknotes were exposed to UVA light for 3 hours and then analyzed with the bioluminometer.

Results :

The simple average of the three untreated banknotes is 1,825 RLU.

The simple average of the three banknotes treated with the solution of EXAMPLE 2 is 48 RLU.

The reduction delta is: 97.38%.

D) Banknote analysis - SARS-Cov-2 virus

Analyses were performed on viral strains according to ISO 18184:2019 "Textiles - Determination of antiviral activity of textile products".

The banknotes were spray-coated with the solution of EXAMPLE

2, spraying two different amounts on the surface to be analyzed, namely 3 g/m² and 6 g/m² with an HVLP system, with a 0.3 mm nozzle, airless model Sata 4400 B.

The procedure includes the comparative analysis between treated samples and three untreated samples.

Before the test, all the samples were sterilized with UV-A rays for 4 hours; Size of treated and untreated samples: 20 x 20 mm;

The viral strain used: SARS-CoV-2_COV2019 ITALY/INMI1;

Volume of test inoculum: 300 uL.

Test temperature: 25°C ± 1°C;

Incubation temperature: 37°C ± 1°C;

Contact time: 1 hour;

Permissive host cell line: VERO E6.

Calculation of the antiviral activity

The antiviral activity is calculated with the following formula:

Mv = lg (V_a) - lg (Vc) (III) where

- M_v is the evaluation of antiviral activity;

- lg (V_a) the logarithm of the average TCID50 of the three replicates at time TO detected on the control;

- lg (V_c) the logarithm of the average TCID₅₀ of the three replicates at time T detected on the treated Log TCID₅₀ inoculum sample: 4.75.

Results :

Treated sample 3 g/m² (% reduction with respect to TO) = 82.22%;

Treated sample 6 g/m² (% reduction with respect to TO) = 94.38%.

The results of the tests are shown in the tables in Figure

5.

E) Artificial aging according to ASTM G155/13. The purpose of the experiment is to simulate accelerated ageing both on plastic samples treated with photocatalytic solutions obtained according to Example 1, and on the samples as such. Such an operation is performed inside the accelerated aging chamber. The aging chamber simulates environmental light and temperature conditions as one of the main causes of material aging.

Test parameters according to ASTM G155/13:

Equipment used: Q-Sun;

Lamps: 3 x 1500 Watt air-cooled xenon lamps;

Filter used: Daylight Q;

Black panel temperature (°C): 63 ±3;

Chamber humidity (%): 65 ±5;

Irradiance at 340 nm (W/m2nm); 0.35

Exposure cycle: 18 minutes of light and rain every 102 minutes of light only;

Test duration (h): 1,000

For the color measurement and to highlight the chromatic variations, we referred to one of the most used systems, the CIELAB system, in which the three coordinates describing the space of colors which the human eye perceives, are indicated with the letters L* (brightness), a* (first coordinated color) and b* (second coordinated color). In the Lab space, then, a color is defined by specifying three coordinates: the brightness L* which goes by convection from 0 (null brightness) to 100 (maximum brightness, in particular the white chosen as reference), the coordinate a* (which expresses red when it is positive and green when it is negative) and the coordinate b* (which expresses yellow when it is positive and blue when it is negative). The coordinates a* and b* can vary from least to most infinite, but for L*=0 and L*=100, a* and b* can only take the value 0.

This color space is used to calculate the visual difference between two colors, DE, using this formula:

DE= (difference between L values)²† (difference between a values)²+ ( difference between b values)² (VI).

Results :

Sample as such: L*=86.58 a*=-14.88 b=60.57

Sample with 10 after l,000h.: L*=85.91 a*=-14.09 b=61.22

DE= 1 .22

In practice, the DE values are a manner for communicating the difference between the two colors.

This list of DE values can serve as a guide for interpreting the psychometric meaning of color differences:

< 0,2: the difference is not perceptible;

Between 0.2 and 0.5: the difference is very small;

Between 0.5 and 1.5: the difference is small;

From 2 to 3: there is a distinguishable color variation;

From 3 to 6: the difference is quite distinguishable;

From 6 to 12: strong chromatic difference, typical of poor quality systems; > 12: means different colors.

Claims

1.A colloidal solution for the antibacterial and antiviral treatment of a substrate, comprising titanium dioxide and one or more mixture additives.

2 . The colloidal solution with the antibacterial and antiviral activity according to claim 1, wherein said solution is an aqueous solution, or an alcoholic solution, or a water/alcohol solution.

3. The colloidal solution with the antibacterial and antiviral activity according to claim 2, wherein said alcoholic solution is based on ethanol.

4 . The colloidal solution with the antibacterial and antiviral activity according to any one of the preceding claims, wherein said titanium dioxide is amorphous photocatalytic titanium dioxide.

5 . The colloidal solution with the antibacterial and antiviral activity according to any one of the preceding claims, wherein said titanium dioxide is selected from:

- titanium dioxide of the Anatase type,

- titanium dioxide of the Rutile type, or

- titanium dioxide of the Brookite type; or from a mixture thereof.

6. The colloidal solution with the antibacterial and antiviral activity according to any one of the preceding claims, wherein said titanium dioxide is included in an amount of about 0.5%-3% (w/w).

7 . The colloidal solution with the antibacterial and antiviral activity according to any one of the preceding claims, wherein said additives can be selected from the group consisting of:

- silver,

- copper,

- calcium.

8. The colloidal solution with the antibacterial and antiviral activity according to claim 7, wherein said silver can be in the form selected from: silver chloride, silver nitrate, silver acetate, silver phosphate glass, silver zeolite, silver copper zeolite, silver sodium hydrogen zirconium phosphate, silver zinc zeolite.

9. The colloidal solution with the antibacterial and antiviral activity according to claim 7, wherein said copper can be in the form selected from: Bis(1-hydroxy-lH- pyridine-2-thionate-O, S)copper (copper pyrithione), Bis(N- cyclohexyl-diazenium-dioxy)-copper, copper hydroxide, copper oxide (I), copper oxide (II), copper sulfate pentahydrate, copper thiocyanate, copper carbonate (II)- copper hydroxide (II) (1:1), powder copper, granular copper.

10 . The colloidal solution with the antibacterial and antiviral activity according to claim 7, wherein said calcium can be in the form selected from: calcium oxide, calcium and magnesium oxide, calcium hydroxide, calcium dihydroxide, caustic lime, hydrated lime, slaked lime, lime, burnt lime, dolomitic lime, Quicklime.

11. The colloidal solution with the antibacterial and antiviral activity according to any one of the preceding claims, wherein said additives can be selected from the group consisting of: Bronopol, salicylic acid, zinc, zinc pyrithione, calcium and magnesium oxide, chlorine dioxide.

12. The colloidal solution with the antibacterial and antiviral activity according to any one of the preceding claims, wherein said additive is silver, in the form of silver chloride, silver acetate or silver phosphate glass.

13. The colloidal solution with the antibacterial and antiviral activity according to any one of the preceding claims, wherein said additive is silver at a concentration from 0.01 mg/1-20 g/1 and preferably about 100 mg/1.

14. The colloidal solution with the antibacterial and antiviral activity according to any one of the preceding claims, wherein said substrate is a paper, metal or plastic substrate.

15. The colloidal solution with the antibacterial and antiviral activity according to the preceding claim, wherein said paper substrate is represented by: banknotes, checks, stamps, tags, revenue seals, meal vouchers, watermarked paper, certificates, diplomas, paper for personal documents, tickets for events, voting cards.

16. The colloidal solution with the antibacterial and antiviral activity according to claim 14, wherein said metal substrate is coins or tokens.

17. The colloidal solution with the antibacterial and antiviral activity according to claim 14, wherein said plastic substrate is identification cards, personal identity documents, driver's license, credit cards, bank cards, plastic cards (even of the magnetic type).

18. A method for preparing the colloidal solution according to any one of claims 1 to 17, comprising the steps of:

I) preparing a photocatalytic titanium dioxide solution;

II) adding one or more additives to the solution obtained in step I) and emulsifying the solution thus obtained at about 11,500 RPM for about 30 minutes.

19. The method for preparing the colloidal solution according to claim 18, wherein in step I) the titanium dioxide is in an amount of about 0.5%-3%, preferably about 0.9-1.2 (w/w) and more preferably about 0.99% (w/w).

20. The method for preparing the colloidal solution according to claim 18 or 19, wherein in step I) said solution is an ethanol solution.

21. A method for treating a substrate with the colloidal solution according to any one of claims 1 to 13, comprising the steps of: - applying the solution according to any one of claims 1 to 13 to a substrate,

- possibly a drying step, at room temperature or by heating, wherein said substrate is a paper, metal or plastic substrate.

22. The method according to the preceding claim, wherein said paper substrate is: banknotes, checks, stamps, tags, revenue seals, meal vouchers, watermarked paper, certificates, diplomas, paper for personal documents, tickets for events, voting cards.

23. The method according to claim 21, wherein said metal substrate is coins or tokens.

24. The method according to claim 21, wherein said plastic substrate is identification cards, personal identity documents, driver's license, credit cards, bank cards, plastic cards (even of the magnetic type).

25. The method for treating a substrate according to any one of the preceding claims 21 to 24, wherein in step I) an amount of colloidal solution from 5 to 15 g/m², preferably 6 g/m², is applied.

26. The method according to any one of the preceding claims from 21 to 25, wherein said application is conducted by spray application or by flexographic printing or by immersion.