JPH039240B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a safety paper that allows easy detection of document alterations caused by chemicals and is therefore effective in preventing such alterations.

The invention is particularly useful for payments and official documents such as checks, banknotes, certificates of deposit, books, income and expenditure statements,
This paper relates to safety papers used in the production of writing paper such as stock certificates, stamps, notarized documents, etc., and in particular to all safety papers used in credit cards, etc. These safety papers are required to ensure that the handwriting and seals are not tampered with in any way by chemicals that brightly erase the colored inks currently used for writing or printing with inking pads.

[Conventional technology]

In addition to watermarks and other physical safety elements such as threads and fibers, traditional safety papers are sensitive to chemicals used to chemically bleach ink and alter handwriting. Contains substances that cause For example, some previously proposed papers include
Acid, alkaline, chlorinated water and Javel water
Chlorine bleach such as Water), ink eraser (French patents 2365656, 2399505, 2402739 (ARJOMARI
French patent 2406027 (Papeteries de VOIRON), French patent 2406027 (Papeteries de VOIRON)
et des Gorges) and "CORECTOR" or "SLOAN'S" type ink erasers.

However, current methods of reducing oxidizing agents and preventing paper tampering inherently employ fluorescent substances, and such fluorescent substances have a handy cap, which limits the safety of the paper. be done. That is, especially since banks and the general public use non-fluorescent materials for signatures. In fact, paper, especially printing and writing paper, is virtually always fluorescent, and fluorescent substances serve as additives to brighten the paper. Non-fluorescent printing - Since writing paper is very difficult to distinguish, counterfeiters will always use fluorescent paper unless they can steal non-fluorescent paper. Therefore, non-fluorescent paper provides an extremely effective defense against counterfeiting. When non-fluorescently treated paper is used, it is essential that the safety agent processed into the paper does not itself exhibit the unavoidable characteristics of a fluorescent material.

Thus, within the scope covered by the present invention, it is imperative that the safety agent be non-fluorescent.

US Pat. No. 2,186,810 discloses a method using non-fluorescent materials. This is because O-phenanthroline or 2,2'-bipyridyl can be used to form complexes with iron () and/or nickel and/or cobalt-containing inks on paper. It leaves an indelible mark. However, this method was effective only with special inks, and it did not show any resistance to attempts to alter the ink used with bleaching chemicals.

[Problems to be solved by the invention and methods for solving them]

An object of the present invention is to obtain a non-fluorescent safety paper that does not react with ink but reacts with a combination of an oxidizing agent and a reducing agent to prevent alteration.
This allows the paper to contain a composition of acids, bases, organic solvents and compounds reactive to erasure, without substantially altering the color of the paper, with respect to a combination of oxidizing and reducing agents on or in its surface; This is an attempt to impart sensitivity to the paper.

We conducted research on a safety agent that satisfies all of the following criteria at the same time.

The paper must be able to be easily and conveniently processed using normal papermaking techniques; - It should not be fluorescent; - It should not add any apparent color to the paper; - It should not significantly increase the cost of the paper. - Sufficient retention in the sheet during its formation and during its movement through the paper machine; - Reactive to oxidizing and reducing agent combinations; - Sufficient to withstand rigorous testing in the field. It has a high sensitivity.

It is clear that such research is difficult when considering that a series of systematic experiments to determine its chromogenic properties under severe test conditions in Example 1 described below did not show satisfactory results. be. For example, it has been found that the following methods cannot be used in practice:

a. Formation of colored iodide by reduction of iodate; - This system uses dangerous metals, e.g. mercury; - Problems with stability of iodate; b. Formation of red lead oxide by oxidation of lead salts. This system also accumulates and uses harmful lead (a problem to be avoided in industry); c. Formation of colored azo compounds by reduction of azoxy derivatives; There is no evidence of any reaction.

After conducting comprehensive research for a long period of time, the applicant discovered that the paper contains a complexing agent that combines with iron () to exhibit a complex color, and that the paper is coated with a reducing agent for document alteration on its surface or inside. By containing iron() which is reduced to iron() and by means of preventing the reduction of iron() to iron() by other constituents of the paper,
It has been found that the object of the invention is achieved.

The selection of the complexing agent is based on its coloring power for the initial product and its reactivity towards the oxidizing agent/reducing agent pair.

The compounding agent is either colorless or slightly colored under papermaking conditions and contains iron().
When used as a means for preventing the reduction of whiteness, the whiteness is not substantially lost.

On the other hand, even if these complexing agents form a complex with the iron() in the paper, the complexing agent is either colorless or slightly colored under papermaking conditions, and the iron() The object is to not substantially lose its whiteness when using means to prevent reduction.

Finally, iron() is reduced once and iron()
Then, these complexing agents must combine with iron() to form a complex color.

Those skilled in the art will have no difficulty in selecting useful compounds according to the above description and criteria.

In order to obtain a white or virtually white non-fluorescent paper according to the invention which is responsive to the combination of oxidizing and reducing agents, the complexing agent is preferably combined with iron() to form a red complex. 2,2'-
Preference is given to using bipyridyl.

Another complexing agent is O-phenanthroline, which is expensive.

The role of the means for reducing iron( ) to iron( ) by other constituents of paper will be easily understood from the following explanation.

Applicant discovered chemical alterations while conducting research on papers sized with starch, containing compounds such as iron(), and containing 2,2'-bipyridyl or O-phenanthroline. It was observed that the color changed over time even though no treatment was applied.

Tests of sheets without starch sizing showed that a stabilized paper was obtained that was stable over time.

Addition of starch to the paper, especially during secondary processing of the sheet by size-pressing, causes discoloration over time.

This coloration is essentially due to the reducing power of the starch, which converts iron() to iron(), promoting the formation of a complex color between iron() and the complexing agent.

This is why the present invention proposes two embodiments as a method for producing paper that is stable over time and does not undergo deterioration under the sizing conditions described below.

A: Conventional sizing, especially with sizing agents that do not reduce iron (), such as polyvinyl alcohol (PVA), which itself contains iron ()
B: Ordinary sizing with a sizing agent that reduces iron, such as starch, which is more oxidizing than the iron () that constitutes the above-mentioned means. Something that binds to the agent.

In this way, the essential aspect of the present invention when the sizing agent is a chemical that reduces iron (), such as starch, is to reduce the be. This oxidizing agent acts as an agent to maintain the starch introduced into the paper in an oxidized state with iron().

The oxidizing agent must be stable under papermaking conditions, and in particular must be stable in water and not stain the paper.

Certain oxidizing agents should be avoided, in particular: iodates, which undergo reduction in air to form colored iodides, chlorates, which pose an explosion risk during manufacture, and boric acids, which are costly. Salt should be avoided.

A person skilled in the art will be able to select an appropriate oxidizing agent from the redox potential table given in the literature based on the above-mentioned criteria, and select a suitable oxidizing agent to prevent the occurrence of side reactions and act as an oxidation state preserving agent. The amount of oxidizing agent required can be determined.

Paper provided with the above-mentioned safety measures according to the invention has good whiteness. If you try to erase what you wrote in ink on this paper with a "CORECTOR" type eraser made of a bisulfite mixture, a colored mark will appear on the area, revealing any tampering. .

Regardless of whether sizing A or B is selected, the paper may be paper formed from cellulose, synthetic or partially synthetic fibers, including coated synthetic paper, and may be of any fiber composition. (hereinafter simply referred to as paper), and may contain the usual fillers used in papermaking, such as inorganic fillers, various additives, binders, resins, color-changing dyes, neutral, acidic or basic A sizing agent, acid sizing, aluminum sulfate for pH adjustment, etc. can be added.

Compounding agents similar to those currently used in safety paper can be added to the above mixture. For example, they act to change the appearance of paper upon contact with acids, bases, erasers, organic solvents, or Jabel water (sodium hypochlorite).

The method of incorporating chemicals into paper according to the present invention includes:
There are three different methods.

- in cellulose or partially or wholly synthetic fiber-based paper; - cellulose paper or partially or wholly synthetic fiber-based soaking method by size-press or off-machine. , - A method for coating all types of paper with the additive according to the invention therein or in each coating layer.

In the present invention, the amount of the chemical to be used is reasonably calculated from its cost as a function of the amount necessary for the complexing agent to participate in the reaction as completely as possible.

The amounts (% by weight) of the chemicals used according to the present invention are as follows.

- Macroscopic amount: at least the stoichiometric amount of iron combined with the paper (dry weight)
0.015% 2,2'-bipyridyl; Maximum amount: determined by expected costs or changes in paper properties in a manner known to those skilled in the art.

Industrially, it is appropriate to add 0.045% by dry weight to the paper.

The reaction reagents are added to the aqueous solution, in which case it is necessary to ensure that the reagents are retained on the fibers in a precipitated, finely dispersed or pigmented state, either by direct binding or by fixatives or binders.

These papers can also contain dyes, in the form of pigments dispersed therein, which are insoluble in water but soluble in organic solvents, and what is written or written on these papers cannot be exposed to organic solvents. It must be prevented from being distorted or altered. Furthermore,
These papers can be decorated with watermark patterns and various other features to make them easier to distinguish.

Thus, according to the present invention, it is possible to produce a white, non-fluorescent, oxidizing and reducing agent combination-sensitive paper, which, when altered by chemical means, has no visible coloration. emerges. The presence of these compositions does not change the appearance of papers already sensitized by conventional techniques or their reactivity.

The paper achieving the object of the invention can be printed by any method, and if it is desired that the writing is permanent and that the possibility of alteration thereof is discovered, then any writing base can be used. It can be used as a material. It is particularly interesting to apply it to non-fluorescent writing paper for payment documents such as checks, certificates of deposit, bankbooks, notarized documents, etc.

Although the majority of safety paper is white, without departing from the purpose of the present invention, the method of the present invention can be applied to prevent tampering with colored paper. The starting material must not have any coloration that would change the color of the paper. Preferably, the iron() complex has a different color or at least a contrasting color than its support.

〔Example〕

The present invention will be explained below with reference to Examples, but is not limited thereto.

Example 1 A paper base material containing 0.015% by weight of ferric chloride () based on the paper was mixed with oxidized starch and 0.35% of sodium persulfate.
The sample was immersed in a bath containing 0.15% by weight of 2,2'-bipyridyl and 0.15% by weight of 2,2'-bipyridyl, and squeezed so that the moisture content was 30%, so that the amount of drug adhering to the paper was 0.045% by weight. The paper thus obtained was brought into contact with a combination of oxidizing and reducing agents as well as "CORECTOR" for ink under the following conditions to cause a color reaction (an extremely rigorous test for the papermaking process). ).

- Soak the paper in 50 g/solution of potassium permanganate for 5 seconds, - Dehydrate for 1 minute, - Soak the paper in 10-15 g/solution of sodium persulfate for the time required to decolorize the permanganate. - Dry in air.

The color of the product obtained was bright pink due to the color change of the starting material paper.

Example 2 Recycling 5-10% of the product waste as described in Example 1 did not affect the whiteness and reactivity of the final product.

Example 3 A paper base containing a dye soluble in an organic solvent and ferric chloride () was treated with oxidized starch, p-nitrophenol, 0.35% by weight of sodium persulfate and 2,2'-
It was immersed in an acidic bath containing 0.15% by weight of bipyridyl to give a moisture content of 30%.

The paper turns pink in response to the tests of Example 1 as well as bases, erasers and organic solvents.

Example 4 Paper base material containing 0.015% ferric chloride ()
Immerse in a bath containing PVA and 0.15% by weight of 2,2'-bipyridyl, squeeze to a moisture content of 30%,
The amount of the drug adhered to the paper was set to 0.045% by weight.

The resulting paper reacts with the ink eraser "CORECTOR" as well as the oxidizing and reducing agent combination used under the test conditions described in Example 1.

Example 5 Recycling 5-10% of the product waste as described in Example 4 did not affect the whiteness and reactivity of the final product.

Example 6 A dye soluble in organic solvents, a base material containing 0.015% by weight of ferric chloride based on paper, PVA, p-nitrophenol, 0.15% by weight of 2,2'-bipyridyl and manganese sulfate. The water content was 30%.

This paper reacted to the tests of Example 1 as well as base, eraser and organic solvents and turned pink.

〔Effect of the invention〕

As is clear from the above, the present invention can provide a secured paper that makes it impossible to alter documents with chemicals.

Claims (1)

[Claims] 1. Iron() ions stabilized with a sufficient amount of oxidizing agent to prevent reduction to iron() ions by the constituent components of the paper, and strong permanent properties due to the presence of iron() ions. an essentially colorless iron() ion complexing agent which produces a pigment, and the stabilized iron() ions combine with said complexing agent when the paper is exposed to an external reducing source. 1. A safety paper characterized in that iron() ions are present in an amount sufficient to generate a permanent visible color. 2. The safety paper according to claim 1, wherein the complexing agent is 2,2-bipyridyl. 3. The safety paper according to claim 1, wherein the complexing agent is o-phenanthroline. 4. Claims 1 to 3, which are sized with an iron ()-reducing sizing agent and contain an oxidizing agent that is more oxidizing than iron () as a means for preventing the reduction of iron () to iron (). Safety paper described in any of the sections. 5. The safety paper according to claim 4, wherein the iron () reducing sizing agent is starch. 6. The safety paper according to any one of claims 4 to 5, wherein the oxidizing agent is sodium persulfate. 7. Claim 1, which is sized with a non-reducing iron() sizing agent as a means of preventing reduction to iron() ions by constituent components of the paper.
- The safety paper described in any of 3. 8 The iron () non-reducing sizing agent is PVA,
The safety paper according to claim 7. 9. Claims 1 to 9, wherein the fiber composition of the paper is pure cellulosic, synthetic fiber-based or a mixture thereof, or is also coated synthetic paper.
Safety paper as described in any of Section 8.