FR2580303A1 - Agent and paper for securing against falsification by a chemical agent, and process for its manufacture - Google Patents

Abstract

The paper contains according to the invention a non-fluorescent means of protecting against chemical falsification which reacts at the oxidising/reducing pair. The paper according to the invention contains iron III and a product which gives a coloured complex with iron II. The attempt at chemical falsification immediately causes the reduction of iron III to iron II followed by the formation of the coloured complex. According to the invention, the complexing agent is preferably 2,2'-bipyridyl. Another complexing agent is orthophenanthroline.

Description

Agent and security paper against falsification by chemical agent, and its manufacturing process.

 The present invention relates to a paper reacting to falsification by chemical agent and its manufacturing process.

 It concerns the field of security papers which can be used in particular for the production of handwritten payment clips and official documents such as checks, paper money, savings bank vouchers, account books, accounting ledgers, titles, papers. stamped, notarial acts, and in particular, all security papers, and comparable security means such as credit cards, etc. for which it is essential to guard against any falsification of the writing or stamp carried on the papers using chemical reagents making it possible to cleanly remove the colored inks currently used for handwriting or printing by ink pads.

Known security papers may, in addition to the watermark and other physical security elements, such as threads, fibers, etc. contain certain reagents bringing awareness to chemical agents which can be used to falsify the writings by chemically bleaching inks. We have for example already proposed papers containing chemical reagents to acids, alkalis, chlorine bleaching reagents, such as Liteau chlorine and bleach, using ink erasers. (Patents
Stationeries ARJOhARI No 2 365656, No 2 399505 No 2 402739 Patent Papeteries de VOIRON et des Gorges No 2 406 027) and reducing oxidizing agents used in erasers of the "COREC-TOR" or "SLOAN'S" type (trade names).

However, the protection of paper against falsification by reducing oxidants has, until now, involved fluorescent products. This fluorescence was a handicap and constituted a limitation of the security of these papers whose non-fluorescence is a sign of recognition very often used, especially at the level of banks and in the general public.

 It is known in fact that papers, in particular for printing-writing, are almost always fluorescent (the fluorescence being due to additives improving the whiteness of the paper). Since non-fluorescent print / write paper can only be found with difficulty, counterfeiters, unless they can divert non-fluorescent paper, will have every chance of using fluorescent paper. Non-fluorescent paper therefore constitutes a very effective prevention of counterfeiting and, when working on such paper which we have managed to make non-fluorescent, it is obviously essential that the security agents incorporated in the paper do not do not bring by themselves the characteristic of fluorescence which we had managed to avoid.

 In the field targeted by the invention, it is therefore absolutely essential that the security agent be non-fluorescent, and the invention finds in particular its originality in that the security agent incorporated in the paper is for the first time times non-fluorescent.

 The invention therefore provides a non-fluorescent security paper reacting to the oxidizing-reducing couple, characterized in that it comprises on its surface or in its mass a chemical composition intended to sensitize the paper vis-à-vis the oxidizing-reducing couples, not significantly modifying the coloring of the paper and compatible with known reagents for sensitizing to acids, bases, organic solvents and erasing pencils.

We therefore sought a security guard who simultaneously meets all of the following criteria - be able to be incorporated into the paper during the
implementation of conventional papermaking techniques,
in a simple and convenient way; - not to be fluorescent - not to color the paper notably - not to increase prohibitively the cost of
paper; - be sufficiently retained in the sheet during the
leaf formation and during the passage of that
ci on paper machine b; - react to the oxidative-reducing couple - with a sufficiently high sensitivity to satisfy
make the severe tests existing in the matter.

 The applicant's choice was first focused on families known for their chromogenic properties under the severe conditions of the test cited in Example 1.

The following means have however proved to be unusable in practice
å) Reduction of an iodate to form a colored indure
- this system involves metals
dangerous, for example mercury
- problem of iodate stability.

b) Oxidation of a lead salt to give a red lead oxide
- this system also involves
lead which is toxic by accumulation
(industrial rejection problem).

c) Reduction of azoxy derivative leading to azo colored products
- molecules corresponding to this system
and specially synthesized by the
plaintiff did not give reactions
expected.

 The Applicant, after intensive and prolonged testing, has finally discovered that certain iron II complexing agents can be used as sensitizing agents.

 According to a characteristic of the invention, the security means developed is based on the formation of colored iron compl-exes after the reduction of the Iron III which has been placed on the surface or introduced into the mass of the security paper during its manufacture.

 According to another characteristic of the invention, the choice of the sensitizing agent will be made according to the coloring power of the initial product and its reactivity with respect to the oxidizing-reducing couple.

 These sensitizing agents will either be colorless or slightly colored under the conditions of production of the paper and will not cause the latter to lose significantly its whiteness qualities 9 in their dose of application.

 On the other hand, if these complexing agents form complexes with the Iron III present in the paper, these complexes will either be colorless or slightly colored in the conditions of production of the paper and will not cause the latter to lose significantly its whiteness qualities. at their application dose.

 Finally, once the.Fer III reduced to Iron II, these sensitizing agents will have to form a colored complex with Iron II.

 Those skilled in the art will be able to select the compounds which can be used without difficulty by means of the information and criteria provided above.

 To obtain a white or practically white non-fluorescent paper according to the invention, offering a reaction to the oxidizing-reducing couple, the sensitizing derivative may in particular be 2,2'-bipyridyl which forms a red complex with Iron II.

 Another sensitizing compound is ortho-phenanthroline which however has the disadvantage of a high cost.

However, the Applicant has observed during its tests on such papers bonded to starch and comprising chemical compounds such as Iron and 2,2'-bipyTidyle or orthophenanthroline a progressive coloring over time in the absence of any attempt at chemical tampering
Tests on sheets free from starch bonding made it possible to obtain security papers which were stable over time.

 The starch added to the paper during the secondary treatment of the sheet, in particular by means of a size press, is at the origin of this progressive coloring over time.

 This coloring is essentially due to the reducing power of the starch which transforms Iron III into Iron II and thus promotes the formation of the colored complex between the Iron in and the complexing agent.

The object of the present application is therefore to propose a method for manufacturing a falsification paper which is stable over time, carried out inter alia under the following bonding conditions.
A - Conventional bonding of security paper using a non-reducing iron III paper bonding agent such as in particular polyvinyl alcohol (pvA), or
B - Classic bonding of paper using a paper bonding agent, iron III reducing agent such as starch, this bonding agent having to be combined with an oxidizing agent.

When the papermaking fining agent is a reducing agent for FerIII such as starch, an essential characteristic of the invention is the incorporation in the impregnation bath of a stronger oxidant than Fer1.11
This oxidant serves as an oxidizing reserve against the starch introduced into the paper.

 This oxidant must be stable under the conditions of production of the paper, in particular be stable in water and must not color the paper.

Certain oxidants are to be avoided in particular
- the iodates which oxidized by the air give colored iodides
- chlorates for the risk of explosions incurred during
the making,
- borates for their costs.

The skilled person will know
- select the appropriate oxidants using the criteria provided below
top and tables of electrochemical potentials available
in scientific literature
- determine the quantity of oxidant necessary to block the
parasitic reactions and constitute an oxidizing reserve.

 The paper comprising such a security means according to the invention has good whiteness. If an attempt is made to eliminate the ink writings on this paper using an eraser of the "00RECTOR" type, a mixture of bisulfite and permanganate, or using a reducing agent alone such as bisulfite or analogues, a colored trace betraying falsification is made to appear in their place.

 Whatever the type of bonding chosen (A or B), this paper can have any fibrous composition, purely cellulosic, partly synthetic, from synthetic fibers or coated synthetic films, more briefly hereinafter "paper", to to which we can add the conventional stationery additives, namely: mineral fillers, various resistance agents, binders, resins, shading dyes, neutral, acid or basic bonding products, alumina sulfate for acid bonding or pH adjustment, etc. .

 To the preceding mixture, it is also possible to add sensitizing reagents analogous to those already used currently in security papers; for example, products ensuring a modification of the appearance of the paper by contact of the latter with acids, bases, erasing pencils, organic solvents or certain oxidants such as bleach (sodium hypochlorite).

The introduction of the reagents according to the invention can be carried out essentially in three different ways
- in the mass of cellulosic paper or of paper in part
or totally synthetic
- by impregnation using a size press or outside the machine
cellulosic papers, or partially or totally synthetic;
- by coating all types of paper, the additive according to
the invention then being contained in the layer (s) of
sleeping.

 The quantities of reagents to be used according to the invention will be calculated for cost reasons as a function of the necessary quantities of complexing agent which we will endeavor to react in full.

The amounts of agents according to the invention (in t by weight) are
- Quantity for observation of a coloration which starts at
be visible to the eye
- 0.015 t dry weight of 2,2'-bipyridile relative to the weight
of paper associated with at least its stoichiometric amount of
Iron III
- Maximum quantity: fixed by the planned additional costs
changes in the characteristics of the paper, in known manner
for the skilled person.

 Industrially, 0.0045 t is introduced by dry weight of 2,2'-bipyridyl based on the weight of paper.

 The reagents are introduced either in aqueous solution in which case it is necessary to ensure their retention on the fibers by direct bonding or by means of fixing agents or binders, or in the microdispersed or pigmented precipitated state.

 These papers may also contain, in their mass, in the dispersed pigmentary state, dyes insoluble in water but organosoluble, so as to preserve the writings or mentions made on these papers against attempts to falsify using organic solvents. In addition, these papers can be watermarked or contain various devices intended to ensure recognition.

 Thus, the invention makes it possible to manufacture a white, non-fluorescent paper, sensitive to the oxidizing-reducing couple, which develops, in the presence of an attempt at chemical falsification, colors detectable with the naked eye on this paper. The presence of these compositions does not entail any significant change in appearance or reactivity of the papers already sensitized by known techniques.

 The paper which is the subject of the present invention can be printed by any of the printing methods and can be used as a handwriting medium when it is desired to have permanence of the particulars entered and to discover possible attempts to falsification of these writings. It is particularly interesting to apply it to the production of non-fluorescent handwritten payment documents such as checks, cash vouchers, savings account booklets, official documents, etc.

 Although most of the security papers used are white, without departing from the subject of the present application, it is possible to envisage incorporating this means of tampering into a security paper, no longer white but colored. The starting materials must not have a coloring which would significantly alter the color of the paper. The Iron complex should preferably have a different color or at least more contrast than that of the support.

 The following examples illustrate the invention without, however, reducing its scope.

- Example 1
A paper support containing by mass ferric chloride in an amount of 0.015 t by weight relative to the weight of paper is impregnated in a bath containing an oxidized starch, sodium persulfate in a proportion of 0.35 5 by weight and 2.2 '-bipyridyle at a rate of 0.15 z by weight so as to deposit, by wet recovery of 30%, 0.045 t by weight of this reagent relative to the weight of paper. One thus obtains a paper reacting to "CXIRECTOR" for ink, as well as to the oxidizing-reducing couple applied under the following conditions (extremely severe test in the profession considered)
- Immersion of the paper for 15 seconds in a 50 g / l solution of
Potassium permanganate.

- draining 1 min of the paper,
- immersion of the paper in a solution containing 10 - 15 g / l of bisulfite
sodium the time necessary for the discoloration of permanganate,
- Drying in the open air.

 The coloration obtained is a pink coloration visibly cutting with the tint of the starting paper.

 The paper obtained also has the advantage of reacting with reducing agents alone, such as bisulfite in aqueous solution at a rate of 10 - 15 g / l by giving a pink reaction.

- Example 2
By proceeding as indicated in Example 1 and by recycling in the mass from 5 to 10 t of broken pieces from previous productions.

 The whiteness and reactivity of the final product are not affected.

- Example 3
A support containing by mass an organosoluble dye, ferric chloride in an amount of 0.015% by weight, is impregnated in an acid bath containing an oxidized starch, paranitrophenol, sodium persulfate in an amount of 0.35% by weight, and 2,2'-bipyridyle at 0.15% by weight so as to have 30% wet recovery.

 The paper reacts to the test of Example 1 by assuming a pink tint, as well as the bases, erasers and organic solvents.

- Example 4
A paper support containing by mass ferric chloride in an amount of 0.015 t is impregnated in a bath containing IVA and 2,2 '-bipyridyl in an amount of 0.15% by weight so as to deposit by wet recovery of 30%, 0, Q45 t of this reagent relative to the weight of paper.

 A paper is thus obtained which reacts to the "CDRECTOR" for ink as well as to the oxidizing-reducing couple applied under the conditions of the test described in Example 1.

- Example S
Eli proceeding as indicated in example 4, and by recycling in the mass from 5 to 10 t of broken pieces of previous productions.

 The final whiteness and reactivity of the final product is not affected.

- Example 6
A support containing by mass an organosoluble dye, ferric chloride in an amount of 0.015 z by weight relative to the weight of paper, is impregnated in an acid bath containing PVA, paranitrophenol, 2,2'bipyridyle at the rate of 0, 15 ee by weight and manganese sulphate so as to obtain 30% wet recovery.

 The paper reacts to the test of Example 1 by assuming a pink tint, as well as the bases, erasers and organic solvents.

Claims (11)

R E V E N D I C A T I O N S  1 - Non-fluorescent security means against chemical falsification, by a reducing chemical agent, of documents drawn up on paper, such as checks, paper money, securities or the like, characterized in that the paper contains FerIII and a sensitizing agent giving a complex colored with FerII.  2 - Safety aloyen according to claim 1 characterized in that the sensitizing agent is 2,2'-bipyridyle.  3 - Security means according to claim I characterized in that the sensitizing agent is orthophenanthroline.  4 - security means according to one of claims I to 3 charac terized in that the paper is bonded with a reducing bonding agent of Iron III and contains a stronger oxidant than Iron  5 - Security means according to claim 4 characterized in that the reducing bonding agent of Iron III is starch.  6 - Safety aloyen according to claim 4 or 5 characterized in that the oxidant stronger than iron here is sodium persulfate.  7 - security means according to one of claims 1 to 3 charac terized in that the paper is bonded with a non-reducing iron bonding agent  8 - Security means according to claim 7 characterized in that the non-reducing bonding agent of Iron III is PVA  9 - Security paper against falsification by chemical agents, characterized in that it contains at least one security means according to one of claims 1 to 3.  10 - Paper according to claim 9 characterized in that its fibrous composition is purely cellulosic or partly cellulosic or completely synthetic including synthetic coated films.  11. - Security documents such as checks, paper money, securities, credit cards and other similar documents against counterfeiting by chemical agents, characterized in that they comprise at least one security paper according to claim 9 or 10.