FR2694772A1 - Counterfeit-proofed foils and security documents obtd. thereby - produced by impregnation with a metallic salt coupled with a co-reactant - Google Patents

Abstract

A foil substrate which is proofed against counterfeiting agents, contg. at least one metallic salt coupled with a co-reactant selected from an organic acid (or salt), acid derivs., aldehyde, ketone or a CO2 precursor. USE/ADVANTAGE - The counterfeit proofing may be applied to a cellulosic or a partly or wholly synthetic substrate, which may also contain e..g mineral fillers or colour units. The substrate may also contain a physical authentication such as a watermark, it is amenable to wiring using ink or ball pens. The sensitivity of the metallic anti-counterfeiting salt (pref. Co or Ni) is greatly improved by the presence of the co-reactant; thus, a strong coloured reaction is obtd. using an organic acid with sodium sulphite or bisulphate and redox coatings (such as Kn/nO4-Ha2So3); use of an aldehyde. Ketone or Co2 precursor gives good sensitivity to redox couplings.

Description

CHEMICAL AGENT INFALSFIABLE SHEET
AND SECURITY DOCUMENT OBTAINED
The present invention relates to a sheet which cannot be forged by chemical agents and also to the security document obtained.

It relates more particularly to the field of security papers which can be used in particular for the production of payment documents or official documents such as bank checks, traveller's checks, books of accounting entries, titles, notarial acts, transport documents, and generally all documents for which it is essential to guard against any chemical falsification of the writings or seals carried on these said documents.

Papers are already known which contain reagents which develop a colored reaction under the action of certain chemical agents used to falsify inscriptions by chemical discoloration of the inks.

In patents FR-A-2365656, FR-A-2399505, FR-E-2402739, papers have been described containing reagents sensitive to falsification agents such as acids, alkalis, chlorinated bleaching agents such as water chlorine or bleach, ink erasers; in particular, pyranine, salt of an oxypyrene trisulfonic acid, which develops a fluorescent yellow coloration under the action of an ink erasing pencil, is used.

In application FR-A-2647820, tamper-proof papers containing particular organic reagents such as rutin trihydrate or narigin hydrate have also been described.

In patent EP-B-174885 a paper has also been described containing the 2-2 'bipyridyl-Fe3 + complex, which is sensitive to pairs of redox falsifications and to reducers such as bisulfite.

In application FR-A-2650606, the use of di or trihydroxy benzene compounds has been described as forging agents, the use of an activator of the colored reaction such as metal salts or oxides, excluding d 'an iron salt II or
III, is envisaged.

In the applications FR-A-2643661, FR-A-2620146 and FR-A-2654446 filed by the Applicant, a paper has been described containing as a falsification agent a metal salt preferably of oxidation state II and in particular a cobalt II salt which gives an orange reaction under the action of sodium bisulfite.

In application EP-A-378029, a paper has also been described containing as a falsification reagent, a cobalt II or III salt, but this salt is associated with a co-reactant of reducing nature and of phenolic structure.

Compared to the use of a cobalt salt alone, the reducing co-reactant of the phenolic type makes it possible to obtain a more intense colored reaction with the oxidation-reduction infalsification couples under the test conditions recommended in the field of tamper-proof papers, however the coloring is not improved for the other forging agents, in particular for sodium sulfite solutions.

The object of the invention is to provide a safety sheet containing a metal salt as a chemical falsifying agent, the sensitivity of this salt towards falsifying agents being improved, that is to say that the reactions colored will be more intense than with salt alone or that colored reactions will take place when they do not exist, in any case imperceptible with salt alone.

A further aim is to provide a sheet protected against the greatest number of falsification chemical agents while using the smallest number of falsification reagents possible.

The Applicant has discovered that the aims of the invention are achieved if the metal salt is combined with a co-reactant chosen from the group formed by organic acids or their salts, organic acid derivatives, compounds having an aldehyde reducing function, compounds having a ketone reducing function, carbon dioxide precursors.

Thus, the invention provides a sheet which cannot be forged by chemical agents, characterized in that it contains at least as an agent for forging a metal salt associated with a co-reactant chosen from the group formed by organic acids or their salts, derivatives of organic acid, compounds having a reducing function aldehyde, compounds having a reducing function ketone, precursors of carbon dioxide.

Preferably the metal salt is chosen from cobalt II or III salts, nickel salts or their mixtures.

As metal salts, it is possible in particular to choose them from chlorides, sulfates, acetates, nitrates, these salts being anhydrous or hydrated.

It is noted that in particular the use of an organic acid, its salt or a derivative makes it possible to obtain a colored reaction of great intensity in particular under the action of a saturated solution of sodium sulfite or under the action of sodium bisulfite or also under the action of redox couples such as the potassium permanganate / sodium bisulfite couple.

It is also noted that in particular the use as co-reactant of a reducing agent having an aldehyde or ketone function or of a carbon dioxide precursor gives in particular the sensitivity of the reaction of the metal salt to redox couples.

Preferably, the organic acids are chosen from carboxylic acids or sulfonic acids.

Preferably the organic acid comprises at least two acid groups. These groups can be identical, for example the acid can only contain carboxylic groups, only sulfonic groups. These groups can also be different, for example the acid can contain groups that are both carboxylic (s) and sulfonic (s).

In particular, the carboxylic acid is chosen from the group formed by tartaric acid, phthalic acid, citric acid, malonic acid, tricarballylic acid, trimelittic acid.

The organic acid derivatives can be chosen from amides, lactams, esters, anhydrides or even acid chlorides.

The anhydrides can be of the purely carboxylic or purely sulfonic type or of the mixed type, for example of the sulfocarboxylic type, formed between the carboxylic and sulfonic acid groups.

According to a particular case of the invention, the anhydride is of the sulfocarboxylic type, in particular it is 2-sulfobenzoic anhydride.

In a particular case of the invention, the organic acid can be chosen from amino acids, and more particularly from glutamic acids or asparagines.

Preferably used as compound having an aldehyde reducing function, butyraldehyde.

In a particular case, the carbon dioxide precursor is a carbonate or a bicarbonate, such as, for example, sodium carbonate or bicarbonate.

According to the invention, the unforgeable sheet is a paper with a purely cellulosic fibrous composition, partly synthetic or possibly purely synthetic. The sheet may also be a plastic film, possibly coated.

The composition of the sheet may contain conventional agents used in stationery such as, for example, mineral fillers, binders, various resistance agents, bonding products, shading dyes.

The chemical falsification reagents according to the invention can be added en masse to the composition of the sheet or placed on at least one face of the sheet by impregnation or by coating.

Preferably, reagents that are soluble in water or in non-or very weakly toxic solvents or in their mixtures are used, these reagents being applied to the sheet by impregnation using a size press.

Some metal salts are colored, however the quantities used to reveal attempts at falsification are small enough not to color the sheet to be protected.

Other adulteration reagents already known and compatible with those according to the invention can be added.

The sheet can also include physical authentication elements such as watermarks, plates, threads or special fibers.

The sheet is printable by any means of printing and is suitable for writing, in particular with an ink pen or with a ballpoint pen.

The invention also relates to the security document obtained from the tamper-evident sheet described above.

The invention will be better understood using the following nonlimiting examples:
COMPARATIVE EXAMPLE 1
An aqueous solution of 1185 g is produced containing - 15 g of cobalt nitrate hexahydrate, - 150 g of starch
A sheet of paper is treated with this solution using a size press. We dry.

The wet take-up of the solution is approximately 40 g per 100 g of paper.

EXAMPLE 2
To 100 g of the solution of Example 1, 2 g of an organic acid which is malonic acid is added.

The sheet is treated as in Example 1.

The reactivity of the sheets obtained according to these examples is tested comparatively by using a saturated sodium sulfite solution as a falsifying agent. For example 2 according to the invention, an orange coloration is obtained which is more intense than that obtained for example 1.

Malonic acid therefore participated in the colored reaction between the cobalt salt and the falsifying agent.

If a leaf is treated with a solution containing only starch and malonic acid, therefore without metal salt, and an attempt is made to falsify it with sodium sulphite, no color reaction develops.

COMPARATIVE EXAMPLE 3
A solution is made as in Example 2, but the acid used is a mineral acid, sulfuric acid.

The colored reaction under the action of a saturated sulfite solution is not more intense than in Example 1.

EXAMPLE 4
Aqueous solutions are produced as in Example 2, the organic acid being a dicarboxylic acid chosen from glutaric acid, citric acid, phthalic acid or tartaric acid, the amount of acid varying between 0 , 5 and 2.5 g per 100 g of the bath of Example 1.

We impregnate papers with these different solutions. We dry.

The treated leaves are tested with a saturated solution of sodium sulfite. In each case, an orange coloration develops, the intensity of the color being much higher than that obtained for example 1.

EXAMPLE 5
A solution is made as in Example 2, but the cobalt salt is replaced by nickel chloride.

We treat a paper as in Example 2.

Under the action of a saturated sulfite solution, an intense pink color develops.

If the paper is impregnated with a solution containing no malonic acid, no coloring develops under the action of the sulfite.

EXAMPLE 6
Solutions are produced as in Example 2, but the co-reactant of the cobalt salt is an amino acid, either L-glutamic acid which has two carboxyl groups, or L-asparagine which has only one carboxyl group.

We impregnate sheets of paper with these different solutions; we dry.

Under the action of a saturated solution of sodium sulfite it develops an intense yellow coloring, whatever the amino acid.

EXAMPLE 7
A solution is produced as in Example 2, but cobalt salt, tricarboxylic acid derived from propane, called tricarballylic acid, is used as co-reactant.

We treat a paper as in Example 2.

Apply a saturated solution of sodium sulfite; a more intense orange color develops than in Example 1.

The potassium permanganate / sodium bisulfite redox couple is applied, there is also an orange coloring, while in the case of Example 1 (case of the cobalt salt alone) there is no clearly visible colored reaction. .

EXAMPLE 8
A solution is made as in Example 2, but the acid used is benzoic acid 1,2,4 tricarboxylic called trimelittic acid.

We treat a paper as in Example 2.

The paper is tested with a saturated sodium sulfite solution, it develops an orange coloring.

EXAMPLE 9
To 100 g of the solution of Example 1, 1.45 g of 2-sulfo-benzoic anhydride (mixed anhydride formed between the carboxylic and sulfonic groups) is added.

We impregnate a sheet and dry it.

The leaf obtained is tested with a saturated sodium sulfite solution, an intense orange reaction develops.

EXAMPLE 10
An aqueous solution is produced containing, relative to the total bath, by weight - 1.25% of cobalt nitrate hexahydrate, - 0.1% of butyraldehyde, - 10% of sodium acetate (buffer solution).

We treat a paper as in Example 2.

Under the action of a saturated solution of sodium sulfite a yellow coloration develops.

Under the action of the potassium permanganate / sodium bisulfite couple, an orange reaction develops.

Under the action of bleach, a green reaction develops.

EXAMPLE 11:
An aqueous composition of 1 kg is produced containing - 11.4 g of cobalt nitrate hexahydrate, - 100 g of sodium carbonate, - 15 g of a latex binder
We layer a plastic sheet with this composition, the
2 quantity deposited dry being 10 g / m2
We test the sheet.

Under the action of a saturated solution of sodium sulfite it develops an orange coloring.

Under the action of the potassium permanganate / sodium bisulfite couple, a greenish-brown reaction develops.

EXAMPLE 13
To 100 g of the solution of Example 1, 1.7 g of tartaric acid and 1 g of manganese sulphate are added (manganese sulphate is a forging agent known for its reactivity with bleach).

We treat a paper as in Example 2.

Under the action of sulfite, an intense orange color is obtained, bisulfite an orange color, bleach a brown color, sodium hydroxide a brown color, an ink eraser pencil, an orange color , of
CORECTOR ink a pink to orange halo.

Claims (13)

1. Sheet which cannot be forged by chemical agents, characterized in that it contains at least as the agent for forging a metal salt associated with a coreagent chosen from the group formed by organic acids or their salts, organic acid derivatives, compounds having an aldehyde reducing function, compounds having a ketone reducing function, carbon dioxide precursors. 2. Sheet according to claim 1, characterized in that the metal salt is chosen from cobalt II or III salts, nickel salts or their mixtures. 3. Sheet according to one of claims 1 to 2, characterized in that the metal salts are chosen from nitrates, chlorides, sulfates, acetates, these salts being anhydrous or hydrated. 4. Sheet according to one of claims 1 to 3, characterized in that the organic acids are chosen from carboxylic acids or sulfonic acids. 5. Sheet according to one of claims 1 to 4, characterized in that the organic acids comprise at least two acid groups. 6. Sheet according to claim 5, characterized in that the carboxylic acids are chosen from the group formed by malonic acid, glutaric acid, phthalic acid, citric acid, tartaric acid, tricarballylic acid, trimelittic acid. 7. Sheet according to one of claims 1 to 3, characterized in that the organic acid derivatives are chosen from amides, lactams, esters, anhydrides, acid chlorides. 8. Sheet according to claim 7, characterized in that the anhydride is 2-sulfo-benzoic anhydride. 9. Sheet according to one of claims 1 to 5, characterized in that the organic acids are amino acids. 10. Sheet according to claim 9, characterized in that the amino acids are chosen from glutamic acids or asparagines. 11. Sheet according to one of claims 1 to 3, characterized in that the compound having an aldehyde reducing function is butyraldehyde. 12. Sheet according to one of claims 1 to 3, characterized in that the carbon dioxide precursors are carbonates or bicarbonates, in particular sodium carbonate or bicarbonate. 13. An unforgeable document characterized in that it is obtained from a sheet according to one of the preceding claims.