FR2620146A1 - MEDIUM, PAPER AND SAFETY DOCUMENT AGAINST CHEMICAL FALSIFICATION AND CONTRAFACON - Google Patents

Abstract

This means of security against the chemical falsification of parts drawn up on paper or on coated synthetic supports comprises at least one cobalt salt of oxidation degree 2, giving an orange reaction in the presence of a sodium bisulphite solution. Advantageously, the cobalt salt is chosen from the group comprising cobalt sulfate, cobalt chloride, cobalt acetate, cobalt nitrate, cobalt thiocyanate, cobalt acetylacetonate.

Description

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  MEDIUM, PAPER AND SECURITY DOCUMENT AGAINST FALSIFICATION

  BY CHEMICAL AGENT AND CONTRAFACON

  The present invention relates to a security means, in particular for paper, reacting to a possible falsification

by chemical agent.

  It mainly concerns the field of usable security documents, for the production of handwritten payment documents and official documents such as, in particular, checks, paper money, Savings Bank notes, account books, accounting books, securities, stamped papers, notarial deeds,

  tickets and, in general, any security papers

  and for similar security measures such as credit cards, etc. For all these security documents, it is necessary to guard against any attempt to falsify the writing or stamp on these papers. Falsification can be mechanical (scrubbing or scraping) or chemical: using chemical agents to cleanly eliminate the colored inks currently used for handwriting or printing

by ink pads.

  The known security papers may, in addition to the watermark and other physical security elements, such as wires,

  fibers, etc ... contain certain reagents providing

  chemical agents that can be used to falsify writing by chemically bleaching inks. For example, papers containing chemical reagents have already been proposed for falsification chemical agents such as acids, alkalis, chlorinated bleaching agents such as chlorine water and bleach, ink-erasing pencils (ARJOMARI documents). A-2,365,656, FR-A-2,399,505, FR-A-2,402,739, Papeteries de VOIRON and Gorges FR-A-2,406,027) and reducing oxidizing agents used in the "CORECTOR" type erasers.

(ARJOMARI EP-A-174 885).

  Among all these forgery agents, sodium bisulfite is a reducing agent effective in erasing: it is

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  used in CORECTOR 0 erasers and can be very effective at blurring or removing blemishes

  by falsifications of so-called "tamper-proof" papers.

  To the inventor's knowledge, there is only one protection system against this type of reagent: the 2-2 'bipyridyl-Fe 3+ pair (see EP-A-174 885) which produces a pink spot to red for any attempt to falsify bisulfite. It is desirable to continue in this line of research by discarding organic products for their toxicity and poor stability and focusing on metal salts, in general more

  chemically stable and less toxic.

  In addition, the protection of paper against falsification

  cations must involve non-fluorescent products. Indeed, fluorescence is a limitation of the security of these papers, because non-fluorescence is a sign of recognition very often used, especially at the banks and the general public. We know that papers, especially for printing-writing, are almost always fluorescent, the fluorescence being due to adjuvants improving the whiteness of the

paper.

  Since the supply of non-fluorescent writing printing paper is closely monitored, counterfeiters, unless they can divert nonfluorescent paper, will have any chance of using fluorescent paper. A non-fluorescent paper is therefore a very effective prevention of counterfeiting and, when working on such a paper that has been managed to render non-fluorescent, it is obviously essential that the security agents incorporated in the paper not bring by themselves

  the fluorescence characteristic that we had managed to avoid.

  The object of the invention is therefore to obtain a bisulfite-reactive non-fluorescent security paper by means of a chemical composition which does not substantially modify the coloring of the paper and which is also compatible with the other known acids, bases, oxidants, erasers

and organic solvents.

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  The applicant, after intensive and prolonged tests, finally retained that the object of the invention could be achieved by incorporating cobalt salts of oxidation state 2 into the paper. Indeed, all cobalt salts of oxidation state 2, once introduced into the paper, give

  sensitivity to bisulfite by an orange-colored reaction.

  This reaction is generalizable to all cobalt salts of oxidation state 2 because, independent of the anion forming the cobalt salt, it only involves the Co 2+ ion which, in combination with a sulfur anion originating from the bisulfite solution, forms a

colored compound in orange.

  Cobalt salts with oxidation state 2 are generally

  However, their introduction into the paper does not affect the original hue of the paper to normal dryness and does not fluoresce. Around 100 C, such a paper takes a blue or purple color, which fades spontaneously and quickly when the paper is returned to ambient atmosphere. This coloration phenomenon, brought about by the presence of cobalt salts of oxidation state 2 in the paper, is visible only at high temperatures; it is therefore not a problem in the daily conditions of use of security papers. On the contrary, this coloration during dewatering of the paper can be used as a heat-authentication system, easy and not

  destructive, a security paper of this type.

  According to the invention, the paper may have any fibrous composition, purely cellulosic, or synthetic part, from synthetic fibers or coated synthetic films, more briefly hereinafter "paper", to which can be added the conventional adjuvants of stationery namely : mineral fillers, various resistance agents, binders, resins, shading dyes, neutral bonding agents, acid or basic, alumina sulphate for acidic bonding or pH adjustment, etc. To the above mixture, it is also possible to add sensitizing reagents analogous to those already used today in the security papers: for example, products providing

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  altering the appearance of the paper by contacting it with acids, bases, erasers, organic solvents or certain oxidants such as bleach (sodium hypochlorite). The cobalt salts being generally very soluble, the introduction of these products according to the invention can be preferably done by impregnation by means of a press

gluing or coating.

  The reaction with bisulfite is noticeable with the naked eye from 20 ppm of cobalt of oxidation state 2 in the paper, but for a very visible and rapid reactivity, industrial doses of between 0.1% and 4% degree cobalt

oxidation 2 are more adequate.

  These papers can also contain in their mass, in the dispersed pigmented state, water-insoluble but organoluble dyes, so as to preserve the writings or mentions made on these papers vis-à-vis attempts of forgery to L' using organic solvents. In addition, these papers may be watermarked or contain various artifices intended to ensure the

recognition.

  Thus, the invention makes it possible to manufacture a white, non-fluorescent paper, sensitive to bisulfite, which develops in the presence of an attempt to chemical falsification of colorations detectable with the naked eye on this paper. The presence of these compositions causes no 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 support when it is desired to maintain the statements made and a discovery of possible

  attempts to falsify these writings. He is particularly

  It is interesting to apply it to non-fluorescent handwritten payment documents such as checks, cash certificates, savings accounts, official documents, etc.

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  Although most of the security papers used are white, it is also possible to incorporate this means of forgery into a security paper no longer white, but

of color.

  The following examples illustrate the invention without

however, reduce the range.

EXAMPLE I

  On a paper support containing en masse reagents (ferric chloride and precipitated manganese ferrocyanide) and one or more disperse organosoluble dyes, these products being intended to give the paper the sensitivity to acids and solvents that can be used to forge the paper, is deposited on the surface by a conventional papermaking technique (sizing press) the coating solution comprising per liter of liquid: - 100 g of starch,

  Cobalt chloride hexahydrate.

  A white paper is obtained which reacts in orange with sodium bisulfite or the consecutive addition of a solution of

  permanganate and sodium bisulfite.

  In addition, the paper, if worn locally around C, takes on a blue hue that disappears in minutes at

the heating stop.

  In addition, the paper thus treated reacts with sodium hypochlorite (brown reaction), acids (blue reaction),

  solvents (colors according to nature of the solvents).

EXAMPLE 2

  On a paper medium of identical composition to Example 1 is deposited on the surface by a conventional papermaking technique (sizing press) the coating solution comprising per liter of liquid: - 100 g of starch,

  - 15 g of cobalt sulfate hydrate.

  Results similar to Example 1 are obtained.

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EXAMPLE 3

  Same process and same results as Example 1 with 18 g of

  cobalt nitrate hydrate instead of cobalt chloride.

EXAMPLE 4

  Same process and same results as Example 1 with 10 g of

  cobalt thiocyanate hydrate instead of cobalt chloride.

EXAMPLE 5

  Same process and same results as Example 1 with 15 g

  cobalt acetate tetrahydrate instead of cobalt chloride.

EXAMPLE 6

  Same process and same results as Example 1 with 15 g

  cobalt acetyl acetonate instead of cobalt chloride.

EXAMPLE 7

  On a banknote type support is deposited on the surface by a conventional papermaking technique (gluing press) the coating solution comprising per liter of liquid: - 100 g of polyvinyl alcohol - 30 g of cobalt chloride hexahydrate

10 g of sodium chloride.

  We obtain a white paper with a very slight pink shade. This paper takes a blue color from 80 C. It is therefore easily authenticated by punctual heating of the paper. The reaction is reversible spontaneously in a few minutes. Furthermore,

  the paper reacts strongly to bisulphite in orange.

EXAMPLE 8

  On a plastic support in high density polyethylene is coated by a conventional papermaking technique (trailing blade, air knife ...) the coating color comprising per liter of liquid: - 400 g of dispersed fillers (kaolin, talc, carbonate ) - 200 g of latex

  30 g of hydrated cobalt chloride.

  The coated plastic is white with a slight hue

  bluish. With heat, a very clear blue color is visible.

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Claims (6)

  1. A means of security against the chemical forgery of parts made on paper or on synthetic coated media such as checks, paper money, securities, identity documents, ticketing or the like, characterized in that it comprises at least one cobalt salt of degree of oxidation 2, giving a reaction   orange in the presence of a solution of sodium bisulfite.   2. Safety means according to claim 1, characterized in that at least one cobalt salt is selected from the group consisting of cobalt sulfate, cobalt chloride, cobalt acetate, cobalt nitrate, thiocyanate cobalt, cobalt acetylacetonate.   3. Paper or synthetic backed security support, characterized in that it contains a security means according to one claims I or 2.   4. Paper according to claim 3, characterized in that the   cobalt is present in doses of between 0.1 and 4%.   5. Paper according to one of claims 3 or 4, characterized   in that it is authenticatable to heat by change reversible coloring.   6. Security document characterized in that it contains   at least one paper according to one of claims 4 or 5.