Use of an epoxy-silicone copolymer, crosslinkable fluid composition containing it and banknote coated with this composition

Abstract

The present invention relates in particular to the use of an epoxy-silicone copolymer, that is to say a polyorganosiloxane provided with branches comprising epoxy functions, for the manufacture of an anti-write surface coating for a banknote.

Description

Title of the invention: Use of an epoxy-silicone copolymer, crosslinkable fluid composition containing it and banknote coated with this composition FIELD OF THE INVENTION

[0001] The present invention lies in the field of security documents. Its main subject is the use of an epoxy-silicone copolymer, a crosslinkable fluid composition containing it and a banknote coated with this composition. STATE OF THE ART

[0002] In the field of security documents and more particularly banknotes, one of the causes of the withdrawal by central banks of some of them is the presence of parasitic inscriptions, generally handwritten, made on the surface of these notes by users, using pens, pencils, felt-tip pens or other writing instruments.

[0003] More than just an aesthetic reason for withdrawal, writing or drawing on a banknote bearing the portrait of a living or deceased person (such as a king, queen, emir, etc.), the representation of a national symbol or a sacred entity, can be perceived in some countries as a real offense.

[0004] Current protective varnishes that are applied to the surface of banknotes provide barrier properties, namely that they oppose the adhesion of dry dirt particles (evaluated by the Fritsch test), the penetration of aqueous substances (resistance to water or hydrophobicity - evaluated by the Cobb test) or greasy substances (resistance to fatty substances, greases or oleophobicity - evaluated by the Test Kit) to the surface and inside of the banknote.

[0005] An example of this is given in document WO2013 / 045496 which describes a high-performance varnish in terms of barrier properties.

[0006] To achieve these high barrier properties, the person skilled in the art may choose, as mentioned in the example above, to test macroscopic characteristics intended to reflect the attacks encountered by banknotes in circulation. But he may also choose to directly measure a physicochemical quantity which will be able to characterize upstream the repellent effects or the ability of a surface to be wetted through, in particular, the measurement of the interfacial tension or surface energy.

[0007] Thus in document WO2014 / 067715, a high-efficiency security document varnishing solution is proposed and its performance is evaluated only by surface tension measurements, the most effective solution having a value less than or equal to 25 mN / m.

[0008] Even if the surface energy of such coatings is very low, which generally reflects the difficulty in adhering to the surface of the security document, the present applicant has curiously noted that such varnishes do not prevent or limit enough the possibility of writing on the banknotes.

[0009] In other words, it is found that it is possible to write relatively easily on the note. Despite this low surface energy and as long as the substance (ink or similar) used for writing is not dry, it may be possible to erase what has been written with certain pens, highlighters or pencils. On the other hand, this is more difficult with a Bic brand ballpoint pen or a marker for example. In addition, after drying, it is found that it is particularly difficult to erase correctly without leaving traces.

[0010] Furthermore, it is easy to understand that a procedure implemented by central banks, consisting of attempting to systematically erase the inscriptions present on the notes, is very difficult, if not impossible to implement, unless machines are developed to clean the notes without damaging them, which would greatly increase the time and costs associated with sorting the notes before putting them back into circulation.

[0011] In a completely different field, it is known to apply anti-graffiti treatments to surfaces such as concrete, wood, masonry work, metal, etc.

[0012] Again, such treatments allow for low surface energy. But the term "anti-graffiti" is misleading. Indeed, writing or applying paint with a brush or spray can (tag) on ​​the surface remains possible, but the treatment implemented allows for more or less easy erasure afterwards. Thus, the graffiti can be made to disappear completely or largely.

[0013] It follows from the above that there is an unresolved need for a surface coating formulation, i.e. varnish applicable to security documents and more particularly to banknotes, which not only has the barrier properties mentioned above (resistance to dry dirt, water and grease), but also anti-write properties which reflect the impossibility, or at least the difficulty, of writing on the previously varnished support, thus dissuading the man in the street from using the notes as "Post-it" (registered trademark), reminders or "vent" towards a personality or a symbol of power.

[0014] The expression "anti-write" properties means the ability of the coating applied to a paper or plastic substrate for banknotes to be resistant to writing. In other words, the inks of pens used during writing attempts tend to remain on the tips of the pens, to form droplets on the surface of the substrate (non-continuous line, water repellency) or to adhere with difficulty. cilement (continuous line but with low intensity and which can "bleed" easily).

[0015] In the context of the present invention, this "anti-write" property has been the subject of an instrumental and visual characterization based both on the ASTM D6578 standard entitled "Determination of Graffiti Resistance", which is adapted to the particularity of security documents, and also on a specific test developed on this occasion to translate the difficulty of writing on the supports and therefore deter attempts at writing. More precisely, the "anti-write" property is the subject of an anti-write note described below. Statement of the invention

[0016] This objective is achieved in accordance with the present invention.

[0017] To this end, the present invention relates firstly to the use of an epoxy-silicone copolymer, that is to say a polyorganosiloxane provided with branches comprising epoxy functions, for the manufacture of an anti-write surface coating for a banknote.

[0018] Preferred, but non-limiting aspects of such use are as follows:

[0019] • said polyorganosiloxane corresponds to one of the following formulas:

[0020] [Chem.l] (formula a)

[0022] formulas in which:

[0023] • R represent hydrocarbon groups which are identical or different from each other, • R1 represent hydrogen atoms or hydrocarbon groups which are identical or different from each other, • R2 represents a hydrocarbon group with at least one carbon atom, a group which may also contain an oxygen atom, • n > 1 and m > 1 and n > m, n and m being whole numbers, • R3 represents a hydrocarbon group with at least one atom of

[0024]

[0025] carbon; X is a carbon atom and its index o is greater than or equal to 0, said polyorganosiloxane corresponds to one of the following formulas: [chem 3] or: (formula c'),

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033] formulas in which: • R4 is a methyl or methylene substituent bridging within the cyclohexyl and chemically stable, the combination of formula (b) and formula (c') being excluded, • said polyorganosiloxane corresponds to formula (c). Secondly, the invention relates to a fluid composition crosslinkable under ultraviolet radiation, characterized in that it comprises a cationic crosslinking matrix, as well as an epoxy-silicone copolymer, that is to say a polyorganosiloxane provided with branches comprising epoxy functions. Preferred, but not limiting, aspects of such a composition include: • said polyorganosiloxane corresponds to one of the following formulas: [Chem. 5] (formula a)

[0034] (formula b),

[0035]

[0036] formulas in which: R represent hydrocarbon groups which are identical or different from each other, R1 represent hydrogen atoms or hydrocarbon groups

[0037]

[0038] identical or different from each other, R2 represents a hydrocarbon group with at least one carbon atom, which group may also contain an oxygen atom, n > 1 and m > 1 and n > m, n and m being whole numbers, R3 represents a hydrocarbon group with at least one carbon atom; X is a carbon atom and its index o is greater than or equal to 0, said polyorganosiloxane corresponds to one of the following formulas: (formula c)

[0039]

[0040]

[0041]

[0042]

[0043]

[0044] formulas in which: • R4 is a methyl or methylene substituent bridging within the cyclohexyl and chemically stable, the combination of formula (b) and formula (c') being excluded, • the cationic crosslinking matrix comprises a cycloaliphatic diepoxide, preferably at least 50% by weight, • said polyorganosiloxane is present at a level of at least 5% by weight, preferably between 5 and 15% and even more preferably between 8 and 12%, • the composition also comprises a PFPE-tetraurethane acrylate mixed with ethyl acetate and butyl acetate, • said PFPE-tetraurethane acrylate is present at a level of at least 0.5% by weight, preferably between 0.5 and 5%, and even more preferably between 2 and 4%. Finally, the present invention relates to a banknote, at least one of its opposite faces of which carries an anti-write surface coating formed of a com position according to at least one of the aspects set out above, and which has undergone crosslinking under ultraviolet radiation.

[0045] A preferred, but not limiting, aspect of such a banknote is as follows:

[0046] • said anti-write surface coating has an anti-write rating

[0047] • greater than 8.5 if said at least one face is printed in intaglio or calendered, or at 4.5 otherwise, • preferably greater than 10 if said at least one side is intaglio or calendered, or 6 otherwise, • and more preferably greater than 13 if said at least one side is printed in intaglio or calendered, or 9 otherwise. DETAILED DESCRIPTION OF THE INVENTION

[0048] I. EVALUATION OF THE ANTI-WRITE PROPERTY OF A VARNISHED BANKNOTE SAMPLE.

[0049] Two evaluations were carried out to characterize:

[0050] - the ease of erasing a mark on a sample according to ASTM D6578 “Determination of Graffiti Resistance”; - the difficulty of writing on the sample using a method specially developed to respond to the problem posed.

[0051] A. MARK REMOVAL TEST ACCORDING TO ASTM D6578 MODIFIED

[0052] i. Equipment associated with the mark removal test according to ASTM D6578 modified

[0053] Microfiber cloths;

[0054] Spectrocolorimeter marketed by the company DATACOLOR model DC45IR;

[0055] Glossmeter marketed by the company BYK model 4450 Micro TRI gloss;

[0056] Tester pencils:

[0057] - PentelPEN black N 50 permanent marker from PENTEL CO. LTD. (hereinafter MIN); - BIC brand SOFTfeel MED blue ballpoint pen (hereinafter SBB); - PILOT brand V Bail 0.5 Pure Liquid Ink red microball pen (hereinafter SMR); - BIC brand WHITEBOARD MARKER VELLEDA green erasable marker (hereinafter MEV); - Pink fluorescent highlighter Art. No. 70 / 56 refillable from the original STABILO BOSS brand (hereinafter SFR).

[0058] The choice of tester pencils as well as the associated references / brands are not fully specified in ASTM D6578. In fact, it is indicated: permanent marker / erasable marker / microball pen / spray paint / grease pencil for coloring.

[0059] The choice was made to replace the last two examples with a blue ballpoint pen and a pink fluorescent highlighter, as it is unlikely that spray paint or a grease pencil could be used to write on banknotes unless one wanted to divert them into a work of art, but this is outside the scope investigated in the present application. Furthermore, the colors were generally chosen to cover a wide spectral range.

[0060] Cleaning agents:

[0061] - MEK (Methyl Ethyl Ketone or Methyl Ethyl Ketone); - Xylene; - Gasoline (mixture of C6-C7 alkanes with a n-hexane content of less than 5%); - IPA (Isopropyl Alcohol or Isopropyl Alcohol); - 5% aqueous sodium phosphate solution; - White cotton dry cloth.

[0062] The preparation of the 5% sodium phosphate solution is done in the following proportions:

[0063] - 5 g of tri-sodium phosphate dodecahydrate; - 95 g of demineralized water.

[0064] i. Carrying out the test

[0065] An area of ​​at least 1cm x 0.5cm is colored with each of the writing means listed above. The lines must dry for at least 24 hours before carrying out the erasure test (do not exceed 48 hours of drying).

[0066] After drying, the mark removal test is carried out with each of the cleaning agents from the list indicated above with the specified cloth. The cleaning agent used is indicated next to the removed mark.

[0067] i. Instrumental evaluations

[0068] The spectrocolorimeter is used to measure the following two characteristics for each mark made (i.e. a total of 30 measurement zones - 5 eraser pencil marks multiplied by 6 different cleaning agents (5 liquid + 1 dry):

[0069] - The AE (color difference): between the area of ​​the sample chosen before making the mark and the residual mark after cleaning. Three measurements are taken at different points of the residual mark and the average is calculated. A mark is considered to be completely erased if the AE < 2. - The gloss ratio ABrillance (measurement at 60°): between the area of ​​the sample chosen before making the mark and the residual mark after cleaning. Three measurements are taken at different points of the residual mark and the average is calculated. The ratio must be > 0.9 to consider that the varnish film has not been altered.

[0070] i. Rating scale

[0071] The following ratings are assigned based on the measured AE and ABrillance results (mark erased if AE < 2 and gloss ratio > 0.9):

[0072] [Tables 1] 10 Dry erasable 9 Erasable with 5% sodium phosphate solution 8 Erasable with IPA 7 Erasable with Gasoline 6 Erasable with Xylene 5 Erasable with MEK 4 Erasable with MEK but loss of gloss (AE < 2 but gloss ratio < 0.9). 3.5 Not erasable with MEK but very significant mark removal (AE: 2 < AE < 4) 3 Not erasable with MEK but significant mark removal (AE: 4 < AE < 6) 2 Not erasable with MEK but slight mark removal visible to the naked eye 1 Not erasable with MEK but slight mark removal and loss of gloss (ratio < 0.9) 0 Not erasable with MEK, no change in appearance

[0073] When half points are applied to scores of 4 and above, this means that the AE with the less aggressive cleaning agent (in decreasing order of aggressiveness: MEK, Xylene, gasoline, IPA and 5% sodium phosphate solution) is close to 2 (2 < AE < 4). For example, if AE < 2 with Xylene and 2 < AE < 4 with gasoline, then the score awarded will be 6.5.

[0074] Although this test stems from an existing standard, the present applicant was able to observe in preliminary tests that the latter was however not sufficient to perfectly characterize the desired anti-write property.

[0075] Indeed, it was found that certain brands of tester pencils, once the ink had dried, could be particularly difficult to erase while paradoxically, it was particularly difficult to write on the treated notes which would result in dissuading a person from any persistent attempt. A second evaluation was thus created to visually characterize the difficulty of writing on a sample.

[0076] A. WRITING DIFFICULTY ASSESSMENT TEST

[0077] i. Testing and Evaluation

[0078] Lines are made in several places on the sheet with each of the tester pencils, exactly as in the ASTM D6578 standard previously described and adapted to the safety document, but in this evaluation it is the behavior of the “fresh” line (i.e. which has just been made) which is evaluated.

[0079] Thus this evaluation is done visually and a mark is applied according to the marking scale detailed in the following paragraph.

[0080] i. Rating scale

[0081] The mark is awarded on the quality of the “fresh” line, in particular on its continuity, its water repellency and its intensity, according to the following cases:

[0082] [Tables2] 0 Continuous and intense line 1 Continuous but weak line 2 Slight water repellency 3 Medium water repellency 4 Light / medium water repellency + weak intensity or strong water repellency 5 Strong water repellency + weak intensity or very strong water repellency

[0083] A. WRITING DIFFICULTY ASSESSMENT TEST

[0084] Given that the deterrent to writing is based on the ease of being able to remove or erase the inscriptions made and to a greater extent on being able to make the support difficult to write on, the choice was made to weight the second criterion with a coefficient of 2 so as to be able to constitute a rating out of 20, that is to say:

[0085] Write-resistant score = (Mark erasure test score according to modified ASTM D6578) + 2 x (Writing difficulty assessment test score).

[0086] I. TESTS FOR EVALUATING BARRIER PROPERTIES

[0087] A. FRITSCH TEST

[0088] The soiling resistance was tested according to the Fritsch test, well known in the world of banknote printing. This test uses a vibrating device where small glass beads spread and encrust a soiling composition based on sand, peat, activated carbon, flour, and glycerin mono-oleate (a fatty substance present in particular in sebum) on a paper sample.

[0089] The test lasts 15 minutes. The luminance of an initially white area is measured several times before and after exposure to the soiling composition. The difference obtained, or AL, makes it possible to characterize the adhesion of the soiling to the banknote: the smaller it is, the better the resistance to dry soiling.

[0090] A. COBB TEST ACCORDING TO ISO 535:2014 STANDARD

[0091] Hydrophobicity is described as the resistance to water penetration but also its ability to repel the latter on the surface called water repellency. Resistance to water penetration is therefore measured using the 60 s Cobb test. This is the quantity of water absorbed by the support in g / m2 using a cylindrical impregnation template over a period of 60 seconds. This is a test which is also common in the paper industry to characterize the absorption of paper.

[0092] A. TEST KIT ACCORDING TO TAPPI T559 STANDARD

[0093] Oleophobicity or resistance to grease is measured using fatty substance exposure tests. The “Kit Test” method uses a mixture of castor oil (fatty substance) and high-boiling solvents, namely toluene (aromatic solvent) and n-heptane (aliphatic solvent).

[0094] Depending on the different proportions of the above-mentioned products, a composition is obtained whose viscosity and surface tension vary inversely to its aggressiveness, i.e. its impregnation capacity.

[0095] A composition rich in castor oil is at the bottom of the scale, while a composition rich in heavy solvents is at the top of the same scale.

[0096] There are 12 compositions. A score of 0 corresponds to zero oleophobicity and a score of 12 to maximum oleophobicity.

[0097] I. PRINTING PROTOCOL

[0098] All samples are overprinted with the tested protective varnishes on 100% cotton vellum paper, white paper but calendered with a white intaglio (without ink) on the front to reflect the classic surface condition of a banknote printed on one side intaglio. The barrier properties of the varnishes are generally increased on the side that has been calendered intaglio (more closed paper).

[0099] The samples are varnished in flexography with a 6 cmVm2 anilox (front / back) and dried under HÔNLE UV lamps with a 200 W / cm mercury spectrum at 65% of their power.

[0100] I. PRELIMINARY WORK

[0101] The present applicant already had a high-performance varnishing solution dedicated to banknotes, in an attempt to resolve the technical problem posed.

[0102] The varnish in question, known under the brand name ULTRA, was therefore tested and compared with a reference known to the fiduciary market and widely used on banknotes, namely the SICPAPROTECT varnish (registered trademark) with reference 889368 marketed by the company SICPA.

[0103] These two varnishes will hereinafter be referred to as “ULTRA varnish” and “reference varnish”.

[0104] Firstly, the barrier properties were evaluated:

[0105] The average front / back results for the barrier properties of ULTRA varnish are as follows:

[0106] [Tables3] Fritsch test (absolute value of AL) Cobb test (g / m2) Test kit (score) Front Back Front Back Front Back ULTRA varnish <5 < 10 <5 < 15 6 5 Reference varnish <5 < 12 < 11 <50 2 2

[0107] Then, the tests described previously were carried out and were supplemented by surface energy measurements (see last line of the table below).

[0108] [Tables4] Reference varnish ULTRA varnish Recto Verso Recto Verso Average score in the erasure test ( / 10) 4.7 2.8 6.2 3.0 Average score for difficulty of writing ( / 5) 0.4 0 0.5 0.3 Score / 20 (difficulty of writing x2) 5.5 2.8 7.2 3.5 Surface energy (mN / m) 32.7 32.0 18.7 13.7

[0109] Surprisingly, despite high barrier properties which are clearly present compared to the reference varnish for a varnish weight of approximately 2 g / m2 per side, the ULTRA varnish does not show the expected anti-write properties.

[0110] In any event, the ULTRA varnish has an anti-write property superior to that of the reference varnish, but this improvement is very limited and therefore needs to be reinforced.

[0111] In an attempt to explain these results, additional measurements were carried out, in particular to evaluate the surface tension. As expected, that of the ULTRA varnish is approximately 2 times lower than that of the reference varnish but, still surprisingly, this does not result in significantly better results with regard to the desired anti-write property.

[0112] The present applicant has therefore undertaken work to understand and test new formulations capable of exhibiting the desired anti-write property and of providing a solution to the problem posed.

[0113] Cationic polymerization varnishes provide generally effective protective coatings on banknotes (such as the reference varnish already mentioned above).

[0114] In addition, the barrier properties of cationic varnishes can be increased by choosing reaction additives in suitable dosages.

[0115] Thus, perfluoropolyether type compounds (characteristics of ULTRA varnish) are very useful for significantly improving barrier properties as previously mentioned but are not very effective in terms of anti-writing.

[0116] A possible alternative would be to use silicon-based additives such as siloxanes, some of which have anti-adhesive properties. These additives were not chosen at random. In fact, in addition to their chemical properties, they have economic and ecological advantages, as well as advantages in terms of safety of implementation, namely:

[0117] - they are classified as non-hazardous, - their flash point is high, notably above 94°C, - their transport by road does not require the Agreement for the Carriage of Dangerous Goods by Road (or ADR), - they do not produce Volatile Organic Compounds (or VOCs), and - their cost is generally lower than that of perfluoro compounds polyether.

[0118] In order to carry out comparative tests on different silicon-based additives, a pre-test with a discriminatory aim was carried out on a sample of siloxane-based additives.

[0119] The table below summarizes the chemical information obtained from the Technical Data Sheets (TDS) and Safety Data Sheets (SDS). Several different products obtained from different suppliers were evaluated at different percentages.

[0120] [Tables5] DOW Sartomer Company BYK Trade name Dowsil AP8041 Xiamete r ACP-10 00 CN 9800 CN 9801 3760 3505 3576 Hereinafter AP8041 ACP-10 00 CN 9800 CN9801 BYK376 0 BYK350 5 BYK35 76 Technical data sheet Amino-functional siloxane polymer for fabric finishing softener 100% active silicone antifoam compound Di-functional aliphatic silicon acrylate oligomer for UV curing applications Hexafunctional aliphatic silicon acrylate oligomer for UV curing applications Polyether modified polydimethylsiloxane (PDMS) Solution of a polydimethylsiloxane modified multi-functional acrylic Solution of a polydimethylsiloxane modified multi-functional acrylic Safety Data Sheet Dimethyl, methyl aminoethylaminoisobutyl siloxane with methoxyl and hydroxyl termination Dimethyl 1 siloxane,hydroxyl-terminated reaction with silica (7 to 8%) / / Polyether-modified polysiloxane Acrylic-functional dimethyl polysiloxane in tripropylene glycol diacrylate Acrylic-functional dimethyl polysiloxane in tripropylene glycol diacrylate,

[0121] The pre-test carried out here and presented below is based, in this upstream step, on the sole difficulty in writing and with only two pencils, namely the microball pen red and the pink fluorescent highlighter because the results with these pencils are discriminating between the different varnishes tested. The reference varnish is the cationic polymerization varnish SICPAPROTECT 889368. The ULTRA varnish is the second reference and incorporates a reactive perfluoropolyether urethane compound with acrylate endings, namely Fluorolink AD 1700 (registered trademark, hereinafter AD 1700) marketed by the company SOLVAY.

[0122] [Tableauxô] SFR MBR Front Back Front Back Reference varnish None None None None Added compounds: 8% AD 1700 (ULTRA varnish) Medium Light to medium Light None to light 1% BYK3576 None None None None 0.5% BYK3760 None None None None 0.3% BYK3505 None None None None 5% CN 9800 None None Light Light 2% CN 9801 None None Light Very light 1% AP8041 None None None None 0.1% ACP-1000 None None None None

[0123] This pre-test confirms the previous results on the reference varnish SICPAPROTECT 889368 and on the ULTRA varnish (reference varnish + 8% of AD 1700), the latter presenting an certainly interesting result on the pink fluorescent highlighter (SFR) but too fair with the red Microball (MBR).

[0124] If the reference varnish is predominantly cationic polymerized, it also includes compounds capable of reacting in radical mode for optimal three-dimensional crosslinking in particular. This is the reaction mode that is implemented with the perfluoropolyether-urethane acrylate additive which gives excellent barrier properties, but not the expected anti-write property, or in any case not in a truly significant dimension.

[0125] For the silicone products tested here and surprisingly despite acrylate functions present on some of them, none provide the desired anti-write property.

[0126] Epoxide ring-opening polymerization via cationic initiation is the main polymerization method used in the reference varnish. Cationic initiation is obtained by means of a cationic photoinitiator with, for example, triarylsulfonium hexafluorophosphate salts (for example, reference Speedcure 992 from Lambson) or diphenyl(4-phenylthio)phenylsulfonium haxefluoroantimonate salts (for example, reference DC 1176 from Comexim) which are irradiated under ultraviolet radiation. The main basic reactive compound is a cycloaliphatic diepoxide with CAS number 2386-87-0 and full name 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate. This compound is available from Cytec (under the brand UVACURE 1500), or from Comexim (under the name DOUBLEMER 420 P).

[0127] The present applicant sought a “twin” compound in terms of chemical functionality, i.e. having reactive epoxide functions and still with a siloxane structure. Thus, polyorganosiloxane compounds functionalized with epoxides were tested.

[0128] Usually these compounds are used to form hydrophobic and non-stick film-forming coatings, for example on paper or synthetic plastic supports to promote the removal of adhesive materials applied to these supports, in particular reversibly, such as labels, adhesive tapes, etc.

[0129] Despite the expected chemical compatibility, it is entirely possible that the addition of these compounds does not allow the expected anti-writing property to be developed as has already been shown above. The fact of using an additive with a reactive chemical function identical to that of the majority cationic reagent at more than 50% by mass in the formulation, the cycloaliphatic diepoxide with CAS number 2386-87-0, could be completely ineffective because it is drowned in the mass, or need to be added in too large a quantity to be economically interesting, or at worst destabilise the formula leading to deleterious or unsuspected effects.

[0130] The same simplified protocol was used with epoxy-silicone additives from the Silcolease (registered trademark) Solventless UV range from ELKEM and reference POLY 204, RCA 200 and POLY 215. SFR MBR Recto Verso Recto Verso Reference varnish None None None None Added compounds: 8% AD 1700 (ULTRA varnish) Medium Light to medium Light None to light 10% POLY 204 Strong Medium Strong Medium 10% RCA 200 Medium Light Medium to Strong Medium 20% POLY 215 Strong Medium Strong Medium

[0132] Encouraging preliminary results were obtained in anti-writing on this simplified test with the compounds cited above, which prompted the applicant to carry out complete tests. The varnishes were applied with a grammage of approximately 1.6 g / m2 on the front and 2.3 g / m2 on the back. The results are presented below:

[0133] [Tables8] Writing medium: MIN SBB MBR MEV SFR Varnish Face * Eff (D Dif (2) Eff (D Dif (2) Eff (D Dif (2) Eff (D Dif (2) Eff (D Dif (2) Reference varnish (VR) R 3.5 0 3.5 0 2 1.5 9 0 5.5 0 V 3 0 1 0 2 0 3.5 0 4.5 0 ULTRA varnish R 6.5 0 5 0 2 2 9 0 8.5 3 V 3.5 0 2 0 1 0 3.5 1 5 2 VR + 10% POLY 204 R 8 5 8 1 2 5 10 4 9 5 V 6.5 2 8 1 2 4 5 2 3.5 2 VR + 15% POLY 204 POLY 204 R 8 3 8 1 2 5 10 1 9.5 5 V 6.5 2 8 1 2 4 7.5 2 6 2 VR + 10% of POLY 204 + 3% of AD 1700 R 8 5 5 1 2 5 10 2.5 9 5 V 8 2 5 1 2 5 5.5 2 5 2.5 VR + 10% RCA 200 R 3 5 3 1 2 5 5.5 5 5.5 5 V 3 1 2 1 2 5 3 0 5 2 VR + 20% POLY 255 R 3 2 3.5 1 2 5 8 1 5.5 5 V 2 0 2 1 2 5 3 0 2 2

[0134] * Face: R for recto and V for verso

[0135] (1) Mark removal test score according to modified ASTM D6578 ( / 10)

[0136] (2) Score on the writing difficulty assessment test ( / 5)

[0137] The results of the 5 tester pencils are summed and averaged to obtain the overall scores below:

[0138] [Tables9] Summary Varnish Face * Eff (D Dif (2) Anti-write rating Reference varnish (VR) R 4.7 0.3 5.3 V 2.8 0.0 2.8 ULTRA varnish R 6.2 1.0 8.2 V 3.0 0.6 4.2 VR + 10% POLY 204 R 7.4 4.0 15.4 V 5.0 2.2 9.4 VR + 15% POLY 204 R 7.5 3.0 13.5 V 6.0 2.2 10.4 VR + 10% POLY 204 + 3% AD 1700 R 6.8 3.7 14.2 V 5.1 2.5 10.1 VR + 10% RCA 200 R 3.8 4.2 12.2 V 3.0 1.8 6.6 VR + 20% POLY 215 R 4.4 2.8 10.0 V 2.2 1.6 5.4

[0139] * Face: R for recto and V for verso

[0140] (1) Mark removal test score according to ASTM D6578 modified ( / 10)

[0141] (2) Score on the writing difficulty assessment test ( / 5)

[0142] Among all the additives tested, POLY 204 is the one that obtains the best results added at 10%, 15% and 10% with 3% of AD1700 additive in the reference varnish. With 10% of POLY 204, the varnish already offers satisfactory anti-write performances compared to the reference varnish and the ULTRA varnish.

[0143] In order to be certain that hidden deleterious effects were not introduced by the addition of POLY 204, the barrier performances according to the tests presented above were evaluated on the following varnishes: reference varnish, ULTRA varnish, reference varnish with 10% POLY 204, reference varnish with 15% POLY 204 and reference varnish with 10% POLY 204 and 3% AD 1700.

[0144] [Tables 10] Fritsch test Cobb test Face varnish test kit * AL Typical deviation mL Typical deviation Note (3) Reference varnish (VR) R -3.87 0.37 10.80 2.50 2 V -11.26 0.62 42.57 5.21 2 ULTRA R varnish -3.86 0.73 4.33 0.40 6 V -8.75 0.90 14.17 0.32 5 VR + 10% POLY 204 R -4.61 1.06 7.30 1.61 4 V -10.35 1.13 22.23 2.85 3-4 VR + 15% POLY 204 R -3.80 0.51 7.73 1.06 4V -11.8 2.09 17.13 1.33 3 VR + 10% POLY 204 + 3% AD 1700 R -3.62 0.41 5.97 0.42 5-6 V -7.56 0.86 13.37 0.45 4

[0145] * Face: R for recto and V for verso

[0146] (3) “xy” indicates a note between notes x and y

[0147] Concerning the dry soiling resistance test (Fritsch), no significant difference is observed between the ULTRA varnish and the varnish incorporating 10% POLY 204. In terms of resistance to water (Cobb) and to fatty substances, it is interesting to note that the varnish with 10% POLY204 is superior to the reference but inferior to the ULTRA. It is also of definite interest to note that the varnish with 10% POLY 204 and 3% FLOROLINK AD 1700 has its performances in the Cobb test equivalent to those of the ULTRA varnish, and its performances in the Kit Test just one point below those of the ULTRA, which is of double interest in terms of efficiency and economy because siloxane additives are cheaper than perfluoro-polyether additives.

[0148] The problem posed in the preamble has therefore been solved thanks to the addition of an epoxidized polyorganosiloxane additive incorporated in a varnish cured by ultraviolet radiation, polymerizing mainly by cationic means. The anti-write property based both on the ease of erasing the lines produced and on the difficulty of making fresh inscriptions on the banknotes is satisfactory with relatively low percentages of additive, while retaining interesting barrier properties, without unsustainably increasing the cost price of the formulation and with substantial environmental gains such as those mentioned above.

Claims

Claims

1.

2. Use of an epoxy-silicone copolymer, i.e. a polyorganosiloxane provided with branches comprising epoxy functions, for the manufacture of an anti-write surface coating for a banknote. Use according to claim 1, wherein said polyorganosiloxane corresponds to one of the following formulas: formulas in which: • R represent hydrocarbon groups which are identical or different from each other, • R1 represent hydrogen atoms or hydrocarbon groups which are identical or different from each other, • R2 represents a hydrocarbon group with at least one carbon atom, a group which may also contain an oxygen atom, • n > 1 and m > 1 and n > m, n and m being whole numbers, • R3 represents a hydrocarbon group with at least one carbon atom; • X is a carbon atom and its index o is greater than or equal to O

3. Use according to claim 1, wherein said polyorganosiloxane corresponds to one of the following formulas: or: (formula c'), formulas in which: R4 is a methyl or methylene substituent bridging within cyclohexyl and chemically stable,

4.

5.

6. the combination of formula (b) and formula (c') being excluded. Use according to claim 3, wherein said polyorganosiloxane corresponds to formula (c). Fluid composition crosslinkable under ultraviolet radiation, characterized in that it comprises a cationic crosslinking matrix, as well as an epoxy-silicone copolymer, that is to say a poly-organosiloxane provided with branches comprising epoxy functions. Composition according to claim 5, characterized in that said polyorganosiloxane corresponds to one of the following formulas: or: formulas in which: • R represent hydrocarbon groups which are identical or different from each other, • R1 represent hydrogen atoms or hydrocarbon groups which are identical or different from each other, • R2 represents a hydrocarbon group with at least one carbon atom, a group which may also contain an oxygen atom, • n > 1 and m > 1 and n > m, n and m being whole numbers, • R3 represents a hydrocarbon group with at least one carbon atom; • X is a carbon atom and its index o is greater than or equal to 0.

7. Composition according to claim 6, characterized in that said polyorganosiloxane has one of the following formulas: formulas in which: R4 is a methyl or methylene substituent bridging within cyclohexyl and chemically stable, the combination of formula (b) and formula (c') being excluded.

8. Composition according to one of claims 5 or 7, characterized in that the cationic crosslinking matrix comprises a cycloaliphatic diepoxide, preferably at least 50% by weight.

9. Composition according to one of claims 5 to 8, characterized in that said polyorganosiloxane is present at a level of at least 5% by weight, preferably between 5 and 15% and even more preferably between 8 and 12%.

10. Composition according to one of claims 5 to 9, characterized in that it also comprises a PFPE-tetraurethane acrylate mixed with ethyl acetate and butyl acetate.

11. Composition according to claim 10, characterized in that said PFPE-tetraurethane acrylate is present at a level of at least 0.5% by weight, preferably between 0.5 and 5%, and even more preferably between 2 and 4%.

12. Banknote, characterized in that at least one of its opposite faces carries an anti-write surface coating formed from a composition according to one of claims 6 to 11 which has undergone crosslinking under ultraviolet radiation.

13. Banknote according to the preceding claim, characterized in that said anti-write surface coating has an anti-write rating greater than 8.5 if said at least one face is intaglio or calendered, or 4.5 otherwise, preferably greater than 10 if said at least one face is intaglio or calendered, or 6 otherwise, and more preferably greater than 13 if said at least one face is intaglio or calendered, or 9 otherwise.