WO2013060947A1

WO2013060947A1 - Security paper that cannot be falsified using redox agents

Info

Publication number: WO2013060947A1
Application number: PCT/FR2012/000434
Authority: WO
Inventors: Andre Honnorat
Original assignee: Honnorat Recherches & Services
Priority date: 2011-10-26
Filing date: 2012-10-10
Publication date: 2013-05-02
Also published as: FR2981955B1; FR2981955A1

Abstract

The present invention relates to a security paper that is unfalsifiable with respect to attempts at falsification with redox combinations based on permanganate, characterized in that it comprises, on its surface or/and in its bulk, barium carbonate and in that it is manufactured with compounds that introduce less than 3% by dry weight relative to the dry weight of paper of salts comprising sulphate or sulphite ions.

Description

SAFETY PAPER INFALSIFIABLE TO OXYDO AGENTS

REDUCING

The invention relates to a tamper-resistant security paper vis-à-vis oxidation-reducing agents. Documents such as checks, vouchers, passports, certain gift vouchers, identity documents and other documents such as medical prescriptions, title deeds and other vital documents contain personalized information that may be modified by counterfeiters. The changes involve using clearing agents to remove variable data from documents and to post new information, a new recipient, or another amount on a check, for example.

The erasing agents used by counterfeiters are all those likely to be found commercially, it is particularly used bleach, acids, bases, redox combinations, solvents and very generally all the products capable of erasing inks such as for example hairsprays, white spirit, brake fluid, liquid stain removers, etc. Among the known tamper-proof products it may especially be mentioned those described in the patent FR 2,650,606 which allow a paper treatment vis-à-vis bases, erasers and alkaline reducing agents or EP 190 087 which more specifically indicates reagents for erasers. EP 494 828 indicates an infalsifiability reaction with respect to sodium sulfite. Acid reactants have been known for many, many years, for example, US 322,130 dated July 14, 1885 or US 643,084 of the year 1900.

Tamper reactions with respect to the redox combinations are known from documents US Pat. No. 4,478,681, EP 174,885 and EP 378,029, all of these solutions, however, have important defects, in particular as regards the toxicity of the compounds. the chemicals used or the instability of the reagents with respect to air oxidation, resulting in paper aging, which results in a significant loss of whiteness and reactivity.

The critical problem today for tamper-proof security papers is to obtain papers that are ^" permanently white and reagents and that do not present significant toxicity to people or the environment.

The tamperproof paper according to the invention aims to respond to this problem for tamper-resistant reactions with respect to redox combinations based on the use of permanganate as an oxidizing agent.

Thus tamperproof security paper vis-à-vis tampering attempts with redox-based combinations based on permanganate is characterized in that it comprises on its surface and / or in its mass barium carbonate, and in that that it is manufactured with components introducing less than 3% by dry weight relative to the dry weight of paper of the salts comprising sulphate or sulphite ions.

The advantages of the tamperproof security paper according to the invention are multiple: the paper obtained is very white and its whiteness is not altered in time since the barium carbonate is insensitive to the oxidation of the air, moreover the product is non-fluorescent which is an added benefit,

because of this stability, the reactions with the redox-reducing agents are also stable over time, unlike all the other security papers whose life is limited,

- Due to its slightly alkaline nature barium carbonate allows the realization of security papers in neutral bonding, which is recognized for its stability over time,

- Because of its specific physical characteristics barium carbonate also brings opacity to paper without the need to add a charge such as titanium oxide for this, this actually results in a saving of material and a lower cost price of paper,

- Finally the product is not toxic and has no impact on people or the environment, its use does not require special precautions, unlike other reagents usually used in security papers. Other features and advantages of the invention will emerge from the description which follows. The invention relates to a paper treated in its mass or on its surface with barium carbonate to be unfalsifiable vis-à-vis erasing agents comprising oxido-reducing combinations based on potassium permanganate as an oxidizing agent. Such combinations in order to erase variable data on documents, written or printed, concern for example:

the application of a mixture of potassium permanganate in an acidified medium, then the application of sodium bisulfite as a reducing agent,

- the application of potassium permanganate, then the application of sodium bisulfite as reducing agent.

The invention also aims to treat the paper so that the redox-based combinations of permanganate applied by the forgers lead to a coloring of the paper which is definitive, irreversible, the paper once colored by a combination such that previously described can not be discolored by the application of another chemical agent, in this the tamper-proof reaction is quite interesting and original.

So that the color reaction in the presence of the redox combination can develop it is essential that the paper has the least possible sulphate or sulphite ions or compounds capable of converting barium carbonate to barium sulfate, which is inactive with respect to said erasing agents.

Such ions are traditionally brought into the paper by the sulphate of alumina which is essential for the development of the paper gluing in an acid medium, the paper must therefore be glued in a so-called "neutral" or "pseudoneutre" medium in the jargon paper, c ie, pasted without the rosin-alumina sulphate mixture.

Another source of sulphate ions in the security papers comes from the addition of manganese sulphate, copper sulphate, cobalt sulphate or compounds bringing salts containing such ions in the paper, these products are especially used. to bring a color reaction against erasing attempts with bleach, alkalis and acids. In order to turn the difficulty and obtain the desired reactions, it is intended to use in the paper manganese chloride or other components which develop the same known reactions without the addition of sulfate ions, according to another variant of the organic components can also be used. substitute for these mineral reagents. The paper in which the infeasible reagent is introduced with respect to the redox combinations is therefore quite particular in its composition which must contain as little sulphate or sulphite ions in its composition and that all along its preparation. Ideally the paper should be free of such ions but in practice this is not possible and a minimal amount is still tolerable.

Thus, according to the invention, the infeasible security paper with respect to the attempts of falsification with redox-based combinations based on permanganate is characterized in that it comprises on its surface and / or in its mass barium carbonate. and in that it is manufactured with components introducing less than 3% by dry weight, based on the dry weight of paper, of salts comprising sulphate or sulphite ions.

Advantageously, the infeasible security paper comprises at least 1% and at most 20% of barium carbonate by dry weight relative to the dry weight of said security paper.

More preferably still, the infeasible security paper comprises between 2% and 10% of barium carbonate by dry weight relative to the dry weight of said security paper and is manufactured with components introducing less than 1% by dry weight relative to the weight. dry paper salts containing sulphate or sulphite ions.

The amount of barium carbonate to be introduced into the paper depends on the level of coloration desired for the infeasible reaction and the amount of sulfite or sulphate ions present in the papermaking process. If such poisons are present in a significant amount, either by input into the pulp, or by introduction to the size-press, or by introduction by a subsequent surface treatment of the paper, for example by coating or by varnishing, the The amount to be introduced of barium carbonate will have to be adapted and higher than if these ions are absent.

The barium carbonate is advantageously introduced into the paper at the time of preparation of the dough, for example in the pulper or in the traditional method of introducing the mass load. The barium carbonate can be introduced in the form of a powder, a "slurry" which is a powder dispersed in water, or manufactured in-situ by a mixture of sodium carbonate in the presence of a soluble salt of barium . Such a preparation produced in situ in the paper pulp has the advantage of coating the paper fibers with barium carbonate with increased reactivity compared to tamper-resistant reactions.

The barium carbonate can also be introduced once the paste has been drained, by the size-press or by any coating device placed in or out of the paper machine, in particular by a coating device, so as to bring the reagent to the surface of the paper.

In developing the paper containing the barium carbonate it has been found advantageous to introduce reagents and additives to enhance the reactivity, whiteness or stability of the paper.

According to the invention tamperproof security paper further comprises calcium carbonate or / and sodium carbonate at least 0.1% by dry weight relative to the dry weight of paper.

Furthermore tamperproof security paper made with barium carbonate is non-fluorescent under lighting in the field of ultraviolet radiation, which is a very important feature in the field considered, and has a whiteness according to ISO 2470-1. at least 75.

The tamperproof security paper according to the invention is very stable with respect to the oxidation of air and with respect to variations in climatic conditions which is also quite particular compared with the papers sold in the field whose stability is very bad. Which poor stability results in a loss of whiteness over time and a corresponding loss of reactivity compared to the erasers used by forgers.

Thus according to the invention tamperproof security paper has a loss of whiteness according to ISO 2470-1 after one month of exposure to the open air under standard conditions of temperature, 23 ° C, and hygrometry , 50%, less than 5% of the value measured at the time of paper manufacture.

In order to produce a tamper-resistant paper that is capable of reacting with many different erasing agents, those skilled in the art may be led to add complementary reagents to the paper, for example to provide a reaction with regard to bleach. , bases, acids or solvents. It has been found advantageous in this option to introduce reagents specifically selected for compatibility with barium carbonate.

According to the invention tamperproof security paper further comprises a cobalt or nickel carbonate at a maximum rate of 5% by dry weight relative to the dry weight of paper. According to the invention tamperproof security paper may further comprise a reagent with respect to acids or / and agents capable of reacting with non-aqueous solvents by developing a colored reaction. Such reagents are known in the field of security papers. As previously indicated, the barium carbonate can be introduced through the surface, coating or any surface coating.

Thus, according to the invention, the tamperproof security paper may contain barium carbonate located in a surface coating, advantageously this barium carbonate is present in a proportion of at least 5% by dry weight of said coating, which coating containing at least one binder capable of maintaining the cohesion of the surface deposit.

Binders capable of maintaining surface cohesion are known in the field, they may be latex, starch, polyvinyl alcohols and any type of polymer conventionally known in the coating field to maintain the cohesion of the surface. layer.

The amount of layer deposited on the paper containing barium carbonate can be chosen in a wide range between 0.5 g / m ² and more than 10 g / m ² depending on the type of security document falsifiable to achieve.

According to the invention, the formed, tamper-evident security paper is non-fluorescent and advantageously comprises calcium carbonate and / or sodium at least 5% by dry weight relative to the dry weight of the surface coating.

Examples of advantageous embodiments of the invention indicated below illustrate the invention.

Example 1

Tamper-resistant test paper of 95 g / m ² made from a paper pulp having 5% dry weight, based on dry fiber, of barium carbonate in the form of a powder introduced into the pulper at the time of pulping said dry fibers. It is further introduced into the paper 5% by dry weight relative to the weight of calcium carbonate fibers.

The paper is mass-bonded with a dimeric alkyl ketene and the amount of sulfate-containing components fed by the paste and the various additives introduced into the paper is less than 1% by dry weight based on the weight of paper manufactured.

The paper is pasted in size-press with a starch solution.

Thus manufactured the paper is reactive in pink / purple with the following redox combination applied in two steps: 1) application of an aqueous solution comprising 5% by weight potassium permanganate mixed with 1% sulfuric acid,

2) application of a saturated solution of sodium bisulfite in water.

The coloration developed with this mixture is irreversible with respect to the action of other erasing agents subsequently added.

The non-fluorescent paper thus manufactured has a whiteness measured at 80 according to ISO 2470-1, which is very high compared to the usual security papers. The whiteness of the formed paper evolves almost no time, there is less than 1% loss of whiteness compared to the initial value measured at the time of manufacture, after a storage time of one month under the standard standardized conditions of 50% relative humidity and 23 ° C.

Example 2

Tamper-resistant paper of a grammage of 90 g / m ² for use as a gift voucher, comprising personalization, made with a paste comprising 5% by dry weight of calcium carbonate relative to the dry paste and surface-coated in size-press with a composition comprising, in percentage with respect to the bath weight of barium carbonate at 8% and 1% of sodium carbonate, so as to retain in the finished paper of the order of 3% of dry barium carbonate relative to the dry weight of paper and 0.4% of sodium carbonate. The size-press preparation further comprising a starch-type binder at a level of 12% dry relative to the weight of the preparation.

The carrier paper has less than 1% by dry weight of sulfation or sulfite ion-yielding compounds based on the weight of dry paper and the size-press composition is free of such ions.

Thus manufactured the paper is reactive in pink / purple with the following redox combination applied in two steps:

1) application of an aqueous solution comprising potassium permanganate at 5% by weight,

2) application of a saturated solution of sodium bisulfite in water. Example 3

The tamperproof paper for check described in Example 1 is made under the same conditions for the production of the support containing barium carbonate, the dry quantity being provided at height. of 3% based on the weight of fibers and 10% by weight of calcium carbonate is added, the paper contains less than 0.5% by weight of components bringing sulphate or sulphite ions into the paper. Water-insoluble dyes which are soluble in non-aqueous solvents are added to the dough so as to render the paper tamper-proof with respect to the solvents.

To the sizing press is added cobalt carbonate pre-dispersed in water at a rate of 2% by dry weight relative to the bath weight, which corresponds substantially to 0.8% by dry weight relative to the weight of finished paper . The wet load to the size-press being of the order of 40% relative to the dry weight of the support paper.

1) application of an aqueous solution comprising 5% by weight potassium permanganate mixed with 1% sulfuric acid,

2) application of a saturated solution of sodium bisulfite in water.

The paper is also reactive with solvents, with bleach and strong bases, developing color reactions easily noticeable to the naked eye.

The paper thus manufactured is non-fluorescent under UV illumination at 365 nm. Example 4

60 g / m ² security paper comprising a non-fluorescent support loaded with 10% by weight of calcium carbonate relative to the total weight of the paper, coated off the paper machine with a composition comprising barium carbonate and a latex styrene butadiene carboxylated so as to deposit a dry layer of 10 g / m ² with 4 g / m ² of barium carbonate, or 40% of the dry weight deposited on the surface of the paper. The layer is provided free of components capable of bringing sulphite or sulphate ions into the preparation and the support paper contains less than 3% by dry weight relative to the weight of paper of said components.

1) application of an aqueous solution comprising 5% by weight potassium permanganate mixed with 1% sulfuric acid, 2) application of a saturated solution of sodium bisulfite in water.

The paper thus manufactured is irreversible in relation to permanganate-based redox combinations irreversibly, in the same manner as in the preceding examples. In the four previous examples, it should be noted that the coloration formed between the paper and the redox-reducing combinations may change over time to form a beige, orange or brown coloration depending on the conditions of the tests, depending on the concentrations of the oxidizing and reducing solutions. according to the reducing agents used, according to the reagents or additives included in the paper and in the manner of applying the redox combinations to the paper. All these colors, however, are irreversible compared to the addition of an erasing agent that can be applied later.

Throughout the foregoing description, the term paper should be understood as a flexible porous network, advantageously fibrous, printable and usable for making secure documents, it is preferably a paper machine paper, but the term also encompasses nonwoven products that can be made by a non-papermaking route and the cardboard type materials or various fibrous agglomerates made in one or more jets.

The invention also relates more generally to all security documents incorporating paper and which comprise variable data that can be modified by falsification, according to the invention the documents protected against forgery by means of redox combinations. based on permanganate are characterized in that they incorporate barium carbonate and comprise a maximum level of sulphite or sulphate ions of 3% relative to the weight of the document.

Of course, the invention is not limited to the embodiments described and represented by way of examples, but it also includes all the technical equivalents as well as their combinations.

Claims

1-tamperproof security paper vis-à-vis tampering attempts with redox combinations based on permanganate, characterized in that it comprises on its surface and / or in its mass of barium carbonate and in that It is manufactured with components introducing less than 3% dry weight based on the dry weight of paper of the salts comprising sulphate or sulphite ions.

2- tamperproof security paper according to claim 1 comprising at least 1% and at most 20% of barium carbonate by dry weight relative to the dry weight of said security paper.

Tamper-proof security paper according to claim 2 comprising between 2% and 10% of barium carbonate by dry weight relative to the dry weight of said security paper and manufactured with components introducing less than 1% by dry weight relative to the weight. dry paper salts containing sulphate or sulphite ions.

Tamperproof security paper according to claim 3 further comprising calcium carbonate and / or sodium carbonate at least 0.1% by dry weight relative to the dry weight of paper. 5 tamperproof security paper according to claim 1 characterized in that it is non-fluorescent under illumination in the field of ultraviolet radiation and has a whiteness according to ISO 2470-1 of at least 75.

6 tamperproof security paper according to claim 5, the loss of whiteness according to ISO 2470-1 after one month of exposure to the open air under standard conditions of temperature, 23 ° C, and hygrometry, 50 %, is less than 5% with respect to the value measured at the time of manufacture of said paper.

7 tamperproof security paper according to claim 1 further comprising a cobalt or nickel carbonate at a maximum rate of 5% by dry weight relative to the dry weight of paper.

8 tamperproof security paper according to claim 1 further comprising a reagent with respect to acids and / or agents capable of reacting with non-aqueous solvents by developing a color reaction. 9 tamperproof security paper according to claim 1 wherein the barium carbonate is located in a surface coating and present in an amount of at least 5% by dry weight of said coating, which coating containing at least one binder capable of maintaining the cohesion of the surface deposit.

10 tamperproof security paper according to claim 9 non-fluorescent and comprising calcium carbonate and / or sodium at least 5% by dry weight relative to the dry weight of the surface coating.