FR3071518A1 - PAPER HOLDER, SECURITY DOCUMENT INCLUDING IT, AND METHOD OF MANUFACTURE - Google Patents

Abstract

The present invention relates in particular to a paper medium with a high durability for printing a security document, in particular a bank note, comprising cellulose fibers, in a proportion of at least 50% by weight with respect to the total mass of the paper support in the dry state, additives and adjuvants, at least one binder, and which further comprises at least one oleophobic and hydrophobic agent based on an organic compound containing perfluoropolyether groups (PFPE), according to a concentration greater than 0% and less than or equal to 5% by mass in the dry state relative to the total mass of the paper support in the dry state, characterized in that it furthermore comprises at least one reinforcing agent non-fibrous structural structure of the family of softening agents, that is to say agents increasing the flexibility of cellulose fibers, in an amount of between 0.5% and 15% by weight relative to the total mass of the papic carrier r in the dry state.

Description

® PAPER SUPPORT, SECURITY DOCUMENT INCLUDING THE SAME, AND MANUFACTURING METHOD. @) The present invention relates in particular to a high-durability paper support for printing a security document, in particular a bank note, comprising cellulose fibers, in a proportion of at least 50% by mass per relative to the total mass of the paper support in the dry state, of the additives and adjuvants, at least one binder, and which also comprises at least one oleophobic and hydrophobic agent based on an organic compound containing perfluoropolyether groups (PFPE) , according to a concentration greater than 0% and less than or equal to 5% by mass in the dry state relative to the total mass of the paper support in the dry state, characterized in that it also comprises at least one agent non-fibrous structural reinforcement from the family of softening agents, that is to say agents increasing the flexibility of cellulose fibers, in an amount of between 0.5% and 15% by mass relative to the total mass of the support pa pier in the dry state.

FIELD OF THE INVENTION

The invention relates to a high-durability paper support for printing a security document, in particular a bank note.

The invention also relates to a method of manufacturing this paper support and a security document produced from such a paper support.

TECHNOLOGICAL BACKGROUND OF THE INVENTION

Security documents, particularly banknotes, are subject to numerous requests during their circulation. These can be mechanical in nature, for example folds, creases and other manipulations which can lead to more or less marked deterioration of the fibers or even tears of the latter.

To this must be added the environmental constraints to which the security documents are subject, and one can thus indicate exposure to ultraviolet radiation or drought and especially relative humidity, which can contribute to modifying the behavior of the ticket. Indeed, exposure to a humid environment can cause swelling of the paper, that is to say an increase in its grammage and thickness, accompanied by a decrease in the stiffness of the paper. Conversely, an excessively dry environment can lead to a drop in the humidity of the paper and therefore brittle behavior of its fibers.

It is therefore essential for a paper that it retains its original properties of rigidity but also of general mechanical resistance during its life in the field.

Finally, it should be noted that among the dirt generally present on banknotes, there is a combination of fatty substances generally resulting from sebum and cooking fats transported by humans and transferred from successive holders to the banknote. The accumulation of these fatty substances on the surface of the banknote and even more their penetration into the fibers if the surface of the paper is damaged, contributes to the stickiness of the banknote and to the unpleasant feeling which results therefrom.

Thus, there is a need to protect the surface of the paper, to avoid the accumulation of dirt but also the core of the paper (the fibers) in order to slow down its destructuring and therefore the progression of external aggressors if however the surface protection comes to weaken or even disappear.

This phenomenon is particularly visible at the places of the folds in particular where the fibers are stressed in bending. In these areas, where the surface protection will break under the effect of the crease, there is a need to improve the resistance of the fiber and more particularly its resistance to bending to prevent it from breaking. This slows the risk of breaking or tearing the paper in these weakened areas.

In order to remedy this problem, various methods are already known in the state of the art which make it possible to improve the resistance to soiling and tearing of banknotes.

Thus, for example from document FR 2 975 408, a sheet of high durability paper is known, covered with a protective coating comprising an external printability layer based on polyurethane.

Also known from the prior art, papers with improved resistance, in which are added to the pulp of cellulose fiber, materials such as polyamides, polyesters or polypropylene. We may cite for example the document EP 1 432 576 which describes in particular the use of polyester reinforcing fibers.

Plastic banknotes are also known, for example those produced on bi-oriented polypropylene (BOPP), presented as products ensuring a long longevity and other hybrid products comprising both paper and other parts. plastic based on polyamides or polyesters.

The central banks responsible for issuing, circulating and withdrawing banknotes have budgetary constraints which force them to seek an increase in the longevity of banknotes, in order to reduce the cost of the cycle of the cash, which legitimately turns them to the aforementioned solutions.

However, the substrates obtained with the techniques identified above have various drawbacks:

-Be difficult to print due to the very closed nature of the supports. The inks hardly penetrate into the support and thus their drying and their adhesion to the substrate can be disturbed; this results in certain difficulties during the production of banknotes and sometimes poor resistance of the inks over time. In addition, dull colors may result from these impressions.

- To be difficult to implement during the process of forming the sheet in the wet state. Indeed, the addition of synthetic fibers can disturb or even prevent the creation of bonds between the fibers and therefore completely destructure the sheet of paper.

Finally, in some cases, the varnishing of the support is compulsory to guarantee a minimum hold over time.

As a state of the art, document FR 3 025 532 can also be cited in the name of the present applicant. It describes a paper medium with high durability and biodegradable. It includes an oleophobic and hydrophobic bonding agent, as well as a biodegradable structural reinforcing agent.

In practice, the reinforcing agent consists of additional fibers of different nature, which are added to the cellulose fibers already usually present in the structure of the paper.

Furthermore and in a completely different technical field than that of the present invention, a document is described in document WO 2007/000177 for manufacturing two-ply toilet paper in which, before combining these two plies, at least one applies to a surface of the external sheet a softening composition providing a pleasant contact for the epidermis.

In any event, to date there is a need to have a paper support intended for the manufacture and printing of a security document, in particular a bank note, which has characteristics of high durability, namely high barrier properties as well as high resistance to mechanical stress without modifying the papermaking process, more precisely without adding fibers other than the cellulose fibers usually used for the manufacture of such paper, or disturbing the printing of the support final. More precisely, one seeks on the one hand to increase the flexibility of the fibers, while retaining a relative rigidity of the paper support, so as to increase its resistance to folding and on the other hand to increase its resistance to water and to oil to avoid deterioration of the support by water and fatty substances which are likely to deposit on its surface.

SUMMARY OF THE INVENTION

Thus, the present invention relates to a high-durability paper support for printing a security document, in particular a bank note, comprising cellulose fibers, in a proportion of at least 50% by mass relative to the total mass of the paper support in the dry state, additives and adjuvants, at least one binder, and which also comprises at least one oleophobic and hydrophobic agent based on an organic compound containing perfluoropolyether groups (PFPE), according to a concentration greater than 0% and less than or equal to 5% by mass in the dry state relative to the total mass of the paper support in the dry state,

This support also comprises at least one non-fibrous structural reinforcing agent from the family of softening agents, that is to say agents which increase the flexibility of the cellulose fibers, in an amount of between 0.5% and 15% by mass. relative to the total mass of the paper support in the dry state.

Furthermore, according to other non-limiting and advantageous characteristics of this support:

the Young's modulus of said support, measured according to standard ISO 1924 is reduced by at least 30%, preferably by 50 to 60% compared to a paper support devoid of said structural reinforcing agent;

it has an average value SM / ST of resistance to double ply improved by 100%, and preferably by 200% compared to that of a paper support devoid of said structural reinforcing agent;

the cellulose fiber concentration is greater than or equal to 85% and less than 100% by mass in the dry state relative to the total mass of said paper support in the dry state;

the additives and adjuvants and binder are present at a concentration greater than 0% and less than or equal to 15% by mass in the dry state relative to the total mass of the said paper support in the dry state;

the structural reinforcing agent is chosen from surfactants;

said structural reinforcing agent is chosen from cationic surfactants, in particular from quaternary ammonium compounds and cationic polymers;

said structural reinforcing agent is chosen from nonionic surfactants, in particular from the group consisting of polybutylene, long chain fatty acids, that is to say having a chain length greater than or equal to 10 carbon atoms, and the ethoxylated fatty amino acids;

said structural reinforcing agent is chosen from anionic surfactants; and the perfluoropolyether groups have in their chemical formulas the basic fragments - (CF2CF2O) m- (CF2O) n- where m and n are integers.

The invention also relates to a security document which comprises a support according to one of the preceding characteristics.

Advantageously, said document is a bank note.

Finally, it relates to a process for manufacturing such a paper support which comprises the following steps:

a) cellulose fibers are suspended in water,

b) refining the mixture,

c) addition of additives, adjuvants and binder,

d) purification and filtration of the fibrous suspension,

e) shaping of the paper support,

f) pressing,

g) pre-drying,

h) coating of the paper support,

i) post-drying, and steps for adding structural reinforcing agent (s) and adding oleophobic and hydrophobic agent (s), alone or as a mixture, namely: when they are added alone, that is to say individually: the structural reinforcing agent is added in step c) and the oleophobic and hydrophobic agent in step h), or vice versa; or the two agents are applied one after the other in step h) in line on the paper machine, the first of them being dried by hot air or infrared radiation, before applying the second, even dried by hot air or infrared radiation, when they are added as a mixture, this addition is carried out during step c) or during step h).

Advantageously, the structural reinforcing agents and the oleophobic and hydrophobic agents are applied off-line, separately or as a mixture, by coating, soaking, impregnation, surfacing, spraying, air knife coating, curtain coating, pencil coating, roller coating. engraved, attendants or by transfer, type "size press", "film press", without this list being exhaustive

As shown in the following description, the high durability properties are obtained by a surface treatment which does not require modification of the fibrous composition of the substrate. In addition, the air permeability obtained is not zero, unlike the permeabilities of the majority of high durability supports known currently on the market. In addition, the Cobb bonding value obtained, that is to say the water absorption capacity of the support is normal and comparable to that of a standard paper for banknotes, which confirms its printability. Its printing is therefore facilitated.

Furthermore, the support as described by the invention retains its barrier properties after creasing, with in particular permeability and Cobb values which remain relatively low, unlike untreated paper. These characteristics constitute important parameters which allow the support to better resist mechanical stresses when it is in circulation on the ground.

Finally, the support as described by the invention has increased flexural strength while retaining a normal overall rigidity comparable to standard paper.

DETAILED DESCRIPTION OF THE INVENTION

The fibers used in the composition of the paper support are mainly cellulose fibers.

Advantageously, these cellulose fibers are chosen from fibers derived from hardwoods, softwoods, seasonal plants such as cotton, hemp or flax, for example. These different fibers can be used alone or as a mixture.

Preferably, however, the cellulose fibers used are cotton fibers. This fiber is used for its good physical and mechanical characteristics. Indeed, the long cotton fibers can measure up to 40 mm long, which gives the paper obtained very good resistance to folding.

The paper support according to the invention also comprises non-fibrous additives and adjuvants, preferably chosen from antifoam compounds, mineral fillers, wet strength agents and bonding agents used alone or as a mixture of 'at least two of them.

The anti-foaming compounds are, for example agents such as silicones, silicone emulsions, polyethylene glycol, polyethylene glycol derivatives, synthetic polyalcohols, polyalcohol derivatives, amide-based anti-foaming agents, ester base; surfactants such as oligomers, ethylene oxides (EtO), polypropylene oxides (PPOx); hydrophobic agents such as hydrocarbon waxes, polyethylene waxes, fatty alcohols, fatty acids, fatty esters, ethylenebis (steramide) (EBS), hydrophobic silicas.

These anti-foaming compounds will be added during the preparation of the paper pulp as well as in the wet part of the paper machine, in order to avoid the formation of foam, or even to destroy it and thus improve the formation of the sheet.

Preferably, the mineral fillers are chosen from colloidal silica, sodium silicates, sodium aluminosilicates, natural or precipitated calcium carbonates, talc, natural or calcined kaolin, alumina hydrate, carbon dioxide titanium and barium sulphate, alone or as a mixture of at least two of them.

These mineral fillers are added to modify the optical properties of the paper obtained, such as its whiteness, its gloss or its opacity, but also its surface properties. Some of these fillers are less costly than fibers and are therefore added to reduce manufacturing costs.

Wet strength agents are thermosetting polymers that are added when the paper is still wet and that crosslink in the paper when it is dried. They act as a barrier to water once the paper is made.

Preferably, mainly polymers are used which bond the fibers together, such as urea-formaldehyde resins (UF), melamine-formaldehyde resins (MF), polyamidoamine-epichlorohydrin resins (PAA-E ), glyoxal resins, metal ion complexes alone or as a mixture.

Bonding agents delay the penetration of liquids into the paper. They are implemented either when the paper is still wet (sizing in the bulk of the paper), or at the size press (sizing on the surface).

Preferably, natural products are used, such as modified natural resins (resin-based adhesives), starch or modified starch or synthetic products, such as the alkyl ketene dimer (AKD), the succinic alkenile anhydride (ASA) and other polymers (for example copolymers based on esters of acrylic acid and maleic acid, acrylonitrile and styrene). AKD is the most commonly used bonding chemical and should preferably be used when product specifications permit. It is also possible to use paraffin wax and polyethylene waxes. These different products can be used alone or as a mixture.

As will be described later, the fibers, additives and adjuvants are mixed and are linked together by the use of at least one binder.

This binder improves the resistance of paper in the dry state.

Advantageously, the binder is chosen from polyvinyl alcohols, starch, starches, latex, hemicelluloses, CMCs (carboxymethylcelluloses), galactomannans, gelatins or polyamide-epichlorohydrin resins, taken alone or as a mixture of 'at least two of them.

According to the invention, the paper support also comprises an oleophobic and hydrophobic agent.

This oleophobic and hydrophobic agent is preferably introduced in the form of an aqueous dispersion based on perfluoro-polyethers (PFPE), having in their chemical formulas the basic fragments - (CF ₂ CF ₂ O) _m - (CF ₂ O) _n - where m and n are integers. This agent can for example be chosen from the Fluorolink® PFPE range sold by the company Solvay. Mention may be made, for example, of the commercial product “Fluorolink P56” with an aqueous base.

In accordance with the invention, at least one non-fibrous structural reinforcing agent from the softener family is added to the fibers, additives, adjuvants and binders mentioned above. Throughout the present application is meant an agent which makes it possible to increase the flexibility of the cellulose fibers of the paper. In other words, the Young's modulus of these fibers is reduced and their elongation at break is increased.

Preferably, the structural reinforcing agent is chosen from surfactants such as cationic surfactants, in particular from quaternary ammonium compounds and cationic polymers.

But it can also be chosen from:

- nonionic surfactants, especially in the group consisting of polybutylene, long chain fatty acids, that is to say comprising at least 10 carbon atoms, and ethoxylated fatty amino acids;

- anionic surfactants.

The amount of structural reinforcing agent, which can be described as softening agent, is preferably between 1 and 30% by weight relative to the total weight of the softening composition.

Preferably, the softener solution contains water between 20 and 90%, preferably between 60 and 90%.

It can also contain low molecular weight organic solvents such as polyethylene glycol, ethanol, isopropanol, npropanol, acetone, methyl ethyl ketone ethylene glycol, propylene glycol, glycerin, used alone or mixed. The amount of these solvents can be between 0 and 30%, preferably between 3 and 15%.

This softening agent can be chosen, for example, from the Aquence FiberPlus® range sold by the company Henkel. Examples include the commercial product "Aquence FiberPlus Ultra" or "Aquence FiberPlus Natural".

In accordance with the invention, the previously mentioned products are introduced in the following concentrations:

- Cellulose fibers: greater than or equal to 85% and less than 100%, preferably between 88 to 92%;

- Additives, adjuvants and binders: greater than 0% and less than or equal to 15%, preferably between 8% and 12%;

- Structural reinforcing agent: greater than 0% and less than or equal to 15%, preferably between 0.5% and 3%;

- Oleophobic and hydrophobic agent: greater than 0% and less than or equal to 5%, preferably between 0.5 and 2%;

These percentages are given by dry mass of a given product, based on the total dry mass of the sample considered from said paper support.

An exemplary embodiment of the process for manufacturing the paper support is described in more detail below.

The cellulose fibers are suspended in water. The mixture is then refined to generate small fibrous elements which will allow the fibers to intertwine more easily and the sheet to have excellent mechanical resistance.

In a second step, the various additives, adjuvants and binders are added to the fiber suspension. The structural reinforcing agent can be added at this stage, alone or as a mixture with the oleophobic and hydrophobic agent.

The fibrous suspension is finally purified by gravity to remove impurities, and by filtration to remove fiber agglomerates which could affect the uniformity of the sheet.

If they are not added to the fiber suspension, the oleophobic and hydrophobic bonding agent (s) containing the perfluoropolyether groups and the structural reinforcing agent can be incorporated into the paper support by coating, soaking, impregnation, surfacing, spraying, coating air knife, curtain coating, pencil coating, engraved roller coating, attendants or transfer, "size press", "film press" type, online or offline, alone or in combination.

The sheet forming the paper support can be formed with a machine with a round shape, with or without the addition of a pressurized pre-layer (commonly called in the short form fiduciary industry), or with a simple flat table or bi jet.

A watermark, a safety thread, safety fibers, hilites, planchettes, or markers can be integrated into the paper support during its formation.

Alternatively, the structural reinforcing agents as well as the oleophobic and hydrophobic bonding agents can be applied online or offline and separately, namely that the first product is dried before applying the second product. The application order can be reversed.

According to another variant, the structural reinforcing agents and the oleophobic and hydrophobic bonding agents can be added as a mixture either with the various additives, adjuvants and binders in the fibrous suspension, or by the various coating techniques previously mentioned, in line or offline.

The paper support thus formed is printable and transformable by all known printing and transformation processes and in particular those commonly used in the fiduciary industry (offset, screen printing, intaglio, hot deposition, flexography, typography ...). It is also possible to varnish it before or after printing.

Work has been carried out to observe the durability properties of the paper thus obtained.

Hydrophobicity is characterized as resistance to water penetration and is measured using the Cobb test (60 s), according to ISO standard 535. This is the amount of water absorbed by the support in g / m ² thanks to a cylindrical impregnation template, for a period of 60 seconds. This test is also frequent in the paper industry to characterize the absorption of paper.

The results may give an indication of the printability of the support. Indeed, if the Cobb value is very low, we can expect a refusal of ink from the support. Conversely, with a value that is too high, it can be difficult to achieve the desired rendering in terms of color intensity. The standard values for a banknote are between 40 and 80 g / m ² .

This test was also carried out after "crumpling sec x1" (ie after creasing of the dry support) to evaluate the evolution of the barrier properties of the support after crumpling.

In accordance with this test, the crumpling was carried out once, on the dry sample of dimensions 6.7 x 6.7 cm using a crumpling device developed by the "National Bureau of Standards" and marketed by the company IGT Testing Systems, a device commonly used in the fiduciary field. The sample is wrapped around a fork before being slid into a tube with a cap. This tube is then engaged in a vertical sleeve provided with a solid rod. The tube must then be pushed in until a counterweight is removed from the IGT device, thus applying a force of

100N on the sample. The crumpled sample is then removed by opening the cap. Finally, the sample is gently de-wrinkled manually.

Oleophobia is measured using an exposure test for fatty substances. The method used, called "Kit Test", uses a mixture of castor oil (fatty substance) and high boiling point solvents, namely toluene (aromatic solvent) and n-heptane (aliphatic solvent). ).

Depending on the different proportions of the above-mentioned products, a composition is obtained whose viscosity and surface tension vary inversely with its aggressiveness, that is to say its impregnation capacity.

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 this same scale.

There are 12 compositions and it is recognized that a score greater than or equal to 5 already gives a satisfactory barrier to fat. The evaluation is done visually. The results are highly dependent on the surface condition of the support. In general, the lower the roughness, the better the result in the test kit. For example, it has been observed that after the roughness has decreased, in particular following an intaglio printing, the results of the test kit tend to be improved.

The mechanical resistance of the support has been evaluated by several tests well known in the paper industry in the "Walking" (longitudinal, that is to say in the fiber direction) and "Travers" (transverse, ie - say in the direction perpendicular to the fibers) of the paper indicated respectively SM and ST:

- Double fold resistance with a Frank Prüfgeràte brand device according to ISO 5626;

- Tear resistance initiated according to ISO 1974 standard;

- Dry and wet tensile strength according to ISO 1924-2;

- Wet strength according to ISO 3781.

The rigidity of the support was also evaluated by the Kodak stiffness measurement according to ISO 5629 standard.

Surface properties such as Bendsten roughness and Bendsten air permeability have also been measured, respectively according to ISO 8791-2 and ISO 5636-3 on the front and back sides, thus giving an indication of the printability. of support.

As with the Cobb, the air permeability after crumpling x8 was evaluated to verify the barrier properties after crumpling.

Example 1:

The results obtained with a 100% cotton wove paper support covered on each face with a layer of cationic surfactant (product A which therefore constitutes the structural reinforcing agent) and a layer consisting of oleophobic and hydrophobic agent at 3% in water (product B) (called “high performance solution”) are given in table 1 below. The coating was carried out in 2 stages (product A then product B), by threaded rod on each side of a dry paper already formed with a grammage of 90 g / m ² . The aqueous solution is deposited along the stem then the latter is moved over the sheet to distribute the solution evenly. The threaded rod used deposits a wet layer 6 μm thick. The actual thickness of material obtained is smaller after evaporation of the water during drying. The dry basis weight thus deposited of oleophobic and hydrophobic agent is approximately 0.5 g / m ² per side. That of the fabric softener is approximately 4.5 g / m ² per side.

The results obtained with this high performance solution were compared to paper alone, to paper with only product A, to paper with only product B as well as to high durability paper known in the field of fiduciary printing. The tests are carried out in triplicate and the values indicated are averages.

TABLE 1 (measurements at 23 ° C, 50% RH)

properties Standard Untreated Vellum Paper Competitive solution ¹ high durability Vellum paper + Product A Surface properties Facel Side 2 Face 1 Side 2 Face 1 Face 2 Air permeability (mL / min) ISO 5636-3 Avg. 27.5 0 13.4 E. type 0.2 0 0.6 Air permeability after crumpling (x 8) ISO 5636-3 Avg. 250.9 109.0 102.3 E. type 6.8 10.7 3.9 COBB bonding (g / m ² ) ISO 535 Avg. 134.9 103.0 4.6 5.1 67.5 68.3 E. type 3.7 4.9 0.5 0.3 0.2 7.6 COBB bonding after crumpling (x1) Not standardized Avg. 137.3 120.8 55.9 61.1 107.6 86.6 E. type 11.7 1.9 1.0 4.2 12.3 0.6 Roughness (mL / min) ISO 8791-2 Avg. 459.5 281.3 423 411 634.5 415.5 E. type 44.7 16.0 50.0 67.4 34.9 40.3 Test kit (n °) T559 0 0 11 7 1 1 Mechanical properties SM ST SM ST SM ST Double fold ISO 5626 Avg. 3489 2342 2895 2562 7513 4868 E. type 117 240 361 573 1042 1115 Primed tear resistance (mN) ISO 1974 Avg. 814 881 742 869 906 850 E. type 96 25 83 48 125 40 Kodak stiffness (mN * m) ISO 5629 Avg. 0.62 0.32 0.41 0.23 0.54 0.22 E. type 0.19 0.1 0.01 0.18 0.05 0.04 Young's modulus (MPa) ISO 1924-2 Avg. 4337 1884 4323 2120 1892 380 E. type 104.9 91.3 36.9 103.0 149.3 142.3 Elongation at break (%) ISO 1924-2 Avg. 2.6 4.6 2.8 4.3 3.3 6.4 E. type 0.13 0.21 0.09 0.23 0.08 0.35 Tensile strength in dry state (kN / m) ISO 1924-2 Avg. 8.2 4.4 6.9 3.9 6.9 3.8 E. type 0.4 0.1 0.5 0.1 0.3 0.02 Tensile strength in the wet state (kN / m) ISO 1924-2 Avg. 3.4 1.7 3.4 1.8 3.3 1.7 E. type 0.2 0.4 0.5 0.1 0.2 0.1 Wet strength (%) ISO 3781 Avg. 41.8 38.7 48.9 45.4 48.2 43.9 E. type 2.4 8.9 7.4 4.6 3.8 2.9

¹ This is paper called "Longlife" (registered trademark) from the company Louisenthal

Analysis of Table 1 above shows that the air permeability after crumpling (x8) of the solution according to the invention is more than twice as low as untreated paper, which clearly indicates good destructuring. support.

The solution according to the invention also increases the water resistance by two to three times (depending on the face considered), even after crumpling (crumpling x1) compared to the untreated support.

The treatment applied therefore retains a significant barrier effect even after the support has crumpled.

The surface roughness of the solution is higher, from 40 to 60% depending on the face considered, than the untreated support. This roughness value can be reduced by calendering if necessary.

The oil resistance is significantly improved with a score obtained of 8 in the Test kit on both sides.

Concerning the mechanical properties, the results of the double ply test of the solution according to the invention are more than three times superior to untreated Vellum paper thanks to the structural reinforcing agent which brings flexibility to the fibers.

This improvement in the flexibility of the fibers is confirmed by the drop in Young's modulus of 58% in the running direction and by 70% in the transverse direction, as well as by the increase in elongation at break compared to untreated paper. . The results of dynamic rigidity of the support remain close to the standard values with results little different from those of untreated paper.

The resistance in the wet state is improved by 7% in both the running and cross directions. This characteristic is important for ensuring that banknotes in circulation are kept, especially in humid regions. In fact, in the presence of water, the hydrogen bonds which bind the paper fibers to each other are easily broken and this has the effect of greatly reducing the mechanical resistance of the sheet of paper which will then begin to deconstruct.

The adhesion of the inks to the paper support according to the invention was evaluated for three types of printing characteristic of the production of banknotes: offset, intaglio and letterpress. The resistance of these inks was assessed by a series of chemical (soaking in different chemicals) and mechanical tests.

Among the mechanical tests, there is the "crumpling or crumpling test" which evaluates the resistance to crumpling of the paper support and of the inks printed on the latter in the dry and wet state.

For "wet crumpling", the sample is placed in water for 15 minutes before crumpling. The crumpling is repeated 4, 8 and 40 times on the dry sample and on the wet sample, 4 and 8 times, using an IGT crumpling device described above in the text.

After the tests, the paper and the various prints (offset, 10 fluorescent offset, numbering and intaglio) are assessed visually and the damage is noted from 0 to 4, with the following meanings: 0 = disappearance of the elements, 1 = plus 50% change, 2 = less than 50% change, 3 = slight change, 4 = no change.

The expression “disappearance of the elements” means the total disappearance of the impression, so that it is no longer visible on the ticket.

The results obtained are listed in Table 2 below.

TABLE 2

terms Paper Offset Neon offset under UV 365 Black numbering Soft pruning Chemical resistance Ethanol (C2H5OH) 95% - 30 min 3 4 3 4 4 Oil pure - 30 min 4 4 4 4 4 Acetic acid (CH3COOH) 20% - 30 min 4 4 4 4 4 Sodium hypochlorite (NaCIO) 5% - 30 min 3 4 3 4 4 Hot water 100 ° C - 30 min 3 4 1 4 3 Industrial laundry Water at 100 ° C + 1% St Marc - 30 min 3 3 1 4 3 Mechanical resistance IGT Crumpling sec X4 3 4 4 3 3 IGT Crumpling sec X8 3 4 4 3 3 IGT Wet Crumpling X4- 15 min TA * 3 3 3 3 2 IGT Wet Crumpling X8 - 15 min TA * 3 3 3 2 2 IGT Crumpling sec X40 2 2 2 2 1

(*) = Ambient temperature

The ink holdings are good with results equivalent to those obtained on untreated paper according to the invention. For example, for fluorescent offset, it is common to have scores of 0 or 1 in the hot water and laundry tests on standard untreated paper.

The resistance to crumpling is good, especially after the very aggressive test of 40 crumplings in the dry state (last line).

Overall, the results obtained in this example are satisfactory, the treatment has no negative impact on the hold of the inks on the support and therefore will not require a mandatory post-varnish to reinforce this hold.

Example 2:

In Example 2, the treatment as described by the invention is applied by a coil-coil coating machine with an air gap of width 1300 mm (product A then product B in line), on wove paper 100 % cotton. The machine running speed during the coating was 60m / min.

Product A is dried with hot air ovens before applying Product B itself dried by hot air oven.

The results obtained in this configuration on 100% cotton wove paper are detailed in Table 3. The dry grammages deposited per side were as follows: product A = 1.4 g / m ² , product B = 1.5 g / m ² . The results obtained with the solution according to the invention were compared with untreated paper alone.

TABLE 3 (Measurements at 23 ° C, 50% RH)

properties Standard Untreated paper Longlife competitor solution Surface properties R ° Fifth R ° Fifth Air permeability (mL / min) ISO 5636-3 Avg. 17.5 0 E. type 1.41 0 Air permeability after crumpling (x 8) ISO 5636-3 Avg. 163.3 109 E. type 16.7 10.7 COBB bonding (g / m ² ) ISO 535 Avg. 74.2 79.8 4.6 5.1 E. type 4.5 5.5 0.5 0.3 COBB bonding after crumpling (x1) Not standardized Avg. 103.9 102.8 55.9 61.1 E. type 7.1 8.5 1.0 4.2 Roughness (mL / min) ISO 8791-2 Avg. 621.9 472.9 423 411 E. type 36.5 49.9 50 67.4 Test kit (nj T559 0 0 11 7 Mechanical properties SM ST SM ST Double fold ISO 5626 Avg. 3427 2856 2895 2562 E. type 347 217 361 573 Primed tear resistance (mN) ISO 1974 Avg. 831 944 742 869 E. type 82 106 83 48 Kodak stiffness (mN * m) ISO 5629 Avg. 0.61 0.25 0.41 0.23 E. type 0.04 0.02 0.01 0.18 Young's modulus (MPa) ISO 1924-2 Avg. 3719 1686 4323 2120 E. type 57.4 52.6 36.9 103.0 Elongation at break (%) ISO 1924-2 Avg. 3.1 5.5 2.8 4.3 E. type 0.09 0.16 0.09 0.23 Tensile strength in dry state (kN / m) ISO 1924-2 Avg. 9.2 4.8 6.9 3.9 E. type 0.2 0.2 0.5 0.1 Tensile strength in the wet state (kN / m) ISO 1924-2 Avg. 4.1 1.9 3.4 1.8 E. type 0.2 0.1 0.5 0.1 Wet strength (%) ISO 3781 Avg. 44.6 39.3 49 45 E. type 2.5 1.8 7.4 4.6

The air permeability after creasing (x8) of Example 2 is more than four times lower than untreated paper.

The resistance to water after crumpling (crumpling x1) is also improved: the water absorption is twice lower with the support according to the invention than with the untreated support.

As in example 1, the treatment applied retains its barrier effect even after the support has crumpled.

Oil resistance is improved by five points on the front and back compared to untreated paper. This result is lower than that obtained in Example 1, a result which can be attributed on the one hand to the difference in application technique (bar coating in one case and air knife coating in the other) and, on the other hand, the roughness values of the treated support which are higher than those obtained in Example 1.

Indeed, as previously described in the explanation of the test kit, the surface roughness of the support can have an impact on the resistance to oil. Note that it is possible to reduce the roughness by calendering the support after coating and drying it.

The double fold results of the solution according to the invention are three times greater than standard untreated paper.

Wet strength is also improved: 7% on the front and 6% on the back.

In this example, we show that we can accentuate a property (here the double fold) to obtain very high resistances (average SM / ST> 10,000) by having a correct oil resistance.

By dosing the proportions of agent A and B, it is possible to modify the final properties of the paper as desired.

As in example 1, the adhesion of the inks was evaluated on the paper thus produced for three types of printing characteristic of the production of banknotes: offset, intaglio and letterpress.

The results obtained are detailed in Table 4 below:

TABLE 4

terms Paper Offset Neon offset under UV 365 Black numbering Soft pruning Chemical resistance Ethanol (C2H5OH) 95% - 30 min 3 3 2 3 3 Oil pure - 30 min 3 3 4 4 3 Acetic acid (CH3COOH) 20% - 30 min 3 4 4 4 4 Sodium hypochlorite (NaCIO) 5% - 30 min 3 3 3 4 3 Hot water 100 ° C - 30 min 3 3 1 4 3 Industrial laundry Water at 100 ° C + 1% St Marc - 30 min 3 3 1 3 2 Mechanical resistance IGT Crumpling sec X4 3 3 3 3 3 IGT Crumpling sec X8 3 3 3 3 3 IGT Wet Crumpling X4- 15 min RT 3 3 3 3 3 IGT Wet Crumpling X8 - 15 min RT 3 3 3 3 2 IGT Crumpling sec X40 2 3 3 2 2

The conclusions of Example 1 are confirmed with in particular good 5 crumpling properties even after 40 dry crumplings. The treatment applied does not disturb the adhesion of the inks to the paper.

Example 3

The treatment according to the invention was applied to several wove papers from different suppliers to check the compatibility and the effectiveness of the treatment on different papers.

TABLE 5 properties nor- me Untreated supplier vellum paper 1 Vellum paper supplier 1 treated Untreated supplier 2 vellum paper Vellum paper supplier 2 treated Untreated supplier vellum paper 3 Vellum supplier paper 3 treated Untreated supplier vellum paper 4 Vellum supplier paper 4 treated Surface properties Air permeability a (mL / min) ISO 5636 22.6 9.8 29.8 15.4 23.8 14.6 9 1.9 Mechanical properties SM ST SM ST SM ST SM ST SM ST SM ST SM ST SM ST Double fold ISO 5626 2534 2926 13621 5087 3017 1871 15948 1310 4591 2808 15472 5391 5691 3614 18236 9931

As the table shows:

The treatment is compatible with various Vellum papers.

After processing the papers, the results all show a clear and frank tendency to double fold increase, which, with one exception, shows values 3 to 5 times higher in the forward direction and pr <average in the cross direction.

Regarding air permeability, certain values are low after treatment because paper i has low air permeability.

Claims (14)

1. High durability paper support for printing a security document, in particular a bank note, comprising cellulose fibers, in a proportion of at least 50% by mass relative to the total mass of the paper support in the dry state, additives and adjuvants, at least one binder, and which also comprises at least one oleophobic and hydrophobic agent based on an organic compound containing perfluoropolyether groups (PFPE), in a concentration greater than 0% and less than or equal to 5% by mass in the dry state relative to the total mass of the paper support in the dry state, characterized in that it also comprises at least one non-fibrous structural reinforcing agent of the family softening agents, that is to say agents increasing the flexibility of the cellulose fibers, in an amount of between 0.5% and 15% by mass relative to the total mass of the paper support in the dry state. 2. Paper support according to claim 1, characterized in that the Young's modulus of said support, measured according to ISO 1924 is less than at least 30%, preferably from 50 to 60%, than that of a paper support lacking said structural reinforcing agent. 3. Paper support according to claim 1 or 2, characterized in that it has an average value SM / ST of resistance to double fold greater than 100%, and preferably 200%, than that of a paper support without said structural reinforcing agent. 4. Paper support according to one of claims 1 or 3, characterized in that the concentration of cellulose fibers is greater than or equal to 85% and less than 100% by mass in the dry state relative to the total mass of said dry paper support. 5. Paper support according to one of claims 1 to 4, characterized in that the additives and adjuvants and binder are present in a concentration greater than 0% and less than or equal to 15% by mass in the dry state relative to the total mass of said paper support in the dry state. 6. Paper support according to one of the preceding claims, characterized in that the structural reinforcing agent is chosen from surfactants. 7. Paper support according to one of claims 1 to 6, characterized in that said structural reinforcing agent is chosen from cationic surfactants, in particular from quaternary ammonium compounds and cationic polymers. ' 8. Paper support according to one of claims 1 to 5, characterized in that said structural reinforcing agent is chosen from nonionic surfactants, in particular from the group consisting of polybutylene, long chain fatty acids, ie having a chain length of at least 10 carbon atoms, and the ethoxylated fatty amino acids. 9. Paper support according to one of claims 1 to 5, characterized in that said structural reinforcing agent is chosen from anionic surfactants. 10. Paper support according to one of the preceding claims, characterized in that the perfluoropolyether groups have in their chemical formulas the basic fragments - (CF2CF2O) m- (CF2O) n- where m and n are integers. 11. Security document, characterized in that it comprises a paper support according to one of the preceding claims. 12. Security document according to the preceding claim, characterized in that said document is a bank note. 13. Method for manufacturing a paper support according to one of claims 1 to 10, characterized in that it comprises the following steps: a) cellulose fibers are suspended in water, b) refining the mixture, c) addition of additives, adjuvants and binder, d) purification and filtration of the fibrous suspension, e) shaping of the paper support, f) pressing, g) pre-drying, h) coating of the paper support, i) post-drying, and in that it comprises steps of adding structural reinforcing agent (s) and adding oleophobic and hydrophobic agent (s), alone or as a mixture , namely that: - when added alone, i.e. individually: - the structural reinforcing agent is added in step c) and the oleophobic and hydrophobic agent in step h), or vice versa; or - the two agents are applied one after the other in step h) online on the paper machine, the first of them being dried by hot air or infrared radiation, before applying the second, - even dried by hot air or infrared radiation. - when they are added as a mixture, this addition is carried out during step c) or during step h). 14. The manufacturing method according to claim 13, characterized in that the structural reinforcing agents and the oleophobic and hydrophobic agents are applied off line, separately or as a mixture, by coating, soaking, impregnation, surfacing, spraying, coating at air knife, curtain coating, pencil coating, engraving roller coating, attendants or transfer, "size press", "film press" type.