FR2669948A1 - SECURITY DOCUMENT COMPRISING A SECURITY ELEMENT HAVING PHOTOCHROMIC PROPERTIES. - Google Patents

Abstract

The invention relates to a security document which is not woven integrally comprising at least one security element comprising at least one photochromic compound which reacts reversibly to electromagnetic radiation reaching it and whose wavelength spectrum corresponds to that of the solar spectrum, in a period of time less than 1 minute, for several cycles. The photochromic compound is resistant to temperature up to 120 degrees C and is chemically resistant to oxidizing and / or reducing agents and / or bases and / or acids. Application to paper for banknotes, checks in particular.

Description

SECURITY DOCUMENT COMPRISING A SECURITY ELEMENT HAVING

PHOTOCHROMIC PROPERTIES.

  The invention relates to a security document comprising at least one radiation-responsive security element. It relates more particularly to a security document comprising a security element having photochromic properties, that is to say that this element changes color. reversibly depending on the presence or absence of at least one electromagnetic radiation This security element may be for example in the form of a fiber,

  wire, tape or boards.

  Very often the photochromic products are colorless or almost

  colorless in the absence of certain radiations, especially ultraviolet rays or infra-red rays, and are

the action of these radiations.

  It is known that security documents, for example banknote or check papers or any other valuable document, contain chemical or physical means of authentication.

  and / or indicators of forgery.

  In general, it is known to use, as chemical means, compounds which react with the falsification agents commonly used by falsifiers. These falsification indicator means react, for example, with acids (hydrochloric, citric, acetic, sulfuric, etc.), with bases (including soda),

  oxidizers (bleach), reducing agents and solvents.

  It is also known to use physical means of authentication which are most often the following: the absence of optical brighteners which fluoresce in blue, violet when they are subjected to ultraviolet light, and which are commonly used in the composition of ordinary papers so

to increase their whiteness.

  The presence of watermarks, that is to say a controlled modification of the density of the paper fibers in the thickness thereof, this watermark reproducing a given design which is only perfectly visible in transmitted light, c that is, by transparency. The presence of holograms, moire or other optical effects obtained with optically variable and deposited inks

on the surface of the leaf.

  The punctual presence of elements (for example wires, fibers, boards, etc.) that can be fluorescent and give a fluorescence of various colors, colors or inscriptions or have various physical properties such as magnetism, electrical conductivity, thermomagnetism, etc. Moreover, there are many photochromic compounds

minerals or organic.

  As mineral compounds, mention may be made of silver halides, transition metal salts, tungsten and vanadium acids, optionally doped metal oxides, and the like. As organic compounds, mention may be made of fulgides (derivatives of succinic anhydride), fulgimides (derivatives of succinimide), stilbene derivatives, pyran derivatives, in particular spiropyrans, spirobenzo (or naphtho) pyrans, spiroxazines, hydrazones, oxazones, etc. Such compounds are usually used for glasses (mineral or organic) sunglasses, as described for example in FR-A-2 290 401, EP-A-246 114, FR-A-2 467 182, FR -A-2 450 469 These compounds give the glasses the property of darkening when exposed in full sunlight (

  containing UV rays) and to lighten in the shade.

  These compounds were also used to make documents non-photocopiable They are incorporated in the document en masse or locally to protect an inscription, and when photocopying the document, the light of the photocopier transforms the colorless photochromic into their colored form and we obtain an illegible copy. Such an application is described for example in the applications for

  EP-A-302,774 and US-A-3,597,082.

  Photochromic compounds are also used to make security inks as described in EP-A-327,788, EP-A-248,631 or WO-A-88 01 288 and WO-A-83 00 568. The use of these inks can be used in particular for the authentication of the document on which they are applied However, it can be quite easy to obtain these inks commercially and so it is quite easy to forge the documents by printing with these inks a sheet or map o have been reproduced the others

components of the document.

  It has further been described in European Patent Application EP-A-

  328 320, a security device that can be used to mark articles, packaging or identification cards The security device is a woven material containing one or more threads made of photochromic fibers. This woven material is used as a label that is placed on an authentic article. , such as a garment, bag, fabric, etc. The authentication method is to illuminate the label using a UV lamp to make

  to appear the color of the photochrome.

  It is understood that the recognition process will be performed at the time of sale or resale of a well-known brand object, and this to prevent counterfeiting of luxury goods.

  Authentication will be performed a maximum of two to five times.

  To make such a label, it suffices that the photochromic

  a number of transition cycles of up to 10.

  The patent application JP-A-61 179 399 describes the manufacture of cellulose fibers dyed with photochromic compounds. These fibers are then used as basic fibers for making a document. Therefore, the entire document is photochromic. very expensive because the fibers require for their dyeing a particular compound and significant amounts of photochromic compound. An object of the invention is therefore to provide a security document which is not woven and which comprises at least one security element containing a photochromic compound, this compound being such that the transition from the non-acivated form to the activated form be reversible and

  that the number of transition cycles is very large.

  Indeed this security element is intended for the manufacture for example of banknotes, checks, restaurant vouchers, credit cards, identity cards, passport sheets, etc. It can therefore be used very often, for example several times by day and likely to be subjected to an authentication process at least

  once a week and even at least once a day.

  Another object of the invention is to provide a security document which comprises at least one security element containing a photochromic compound which goes from its non-activated form to its activated form (photo) in a very fast manner. security according to the invention is intended to be authenticated more particularly by the man in the street or for example by a cashier in a payment center If the number of documents to authenticate is important, the user will wish that the color change is In addition, the man in the street will prefer from the outset that the color change is fast

  when using the security document as a means of payment.

  Finally, the security document may for example constitute a passport or identity card sheet and again, when identity verification of many people, the cycle of

  color modification will have to be fast.

  A third object of the invention is to provide a security document which comprises a security element containing a photochromic compound and which is introduced during the manufacture of the document, the security element being an integral part of the document. This is particularly important. because if the element is an integral part of the document it will be very difficult for counterfeiters to

reproduce this document.

  To achieve these goals, several problems arise

the skilled person.

  Those skilled in the art will have to select among photochromic compounds that are commercially available, photochromic compounds which simultaneously have the following properties: a fast and reversible transition to electromagnetic radiation, a high number of transition cycles, a resistance to the physical conditions of manufacture of the support, resistance to forgery agents commonly used by counterfeiters, resistance to aging and more particularly resistance to the rays of natural light, compatibility with the constituents of the security document,

  compatibility with the constituents of the security element.

  The invention therefore aims to provide a non-woven security document integrally comprising at least one security element comprising at least one photochromic compound, the security element having a long life and being easy to authenticate . The security document according to the invention is such that the photochromic compound reacts reversibly to electromagnetic radiation reaching it in a shorter period of time.

  at 1 minute, for several cycles.

  Preferably, the photochromic compound is resistant to a temperature of up to 120 ° C. By resisting, it is meant that the photochromic compound does not lose its passage qualities from the non-activated state to the photoactivated state and vice versa, when it is no

  subjected to or subjected to electromagnetic radiation.

  In addition, the photochromic compound is chemically resistant to oxidizing agents and / or reducing agents such as hydrogen peroxide, sodium hypochlorite, or other alkali metal hypohalides, with strong or weak acids, for example acetic acid. ,

  citric, with strong or weak bases.

  According to a preferred embodiment of the invention, the security element is disposed at least partially between the two faces of the security document. It can be located completely on the surface of the document, or it can be arranged in windows made. in the document Such windows are made in known manner of the prior art as described in EP-A-059 056 The security element can also be completely included between the two faces of the security document, but then, it shall be located at a depth allowing the electromagnetic radiation to reach it to induce the coloring of the photochromic compound. The security element may for example be a wire, a fiber, a board composed of synthetic and / or natural material comprising

  a photochromic compound in bulk or on the surface, uniformly or not.

  It can be provided that the security element comprises the photochromic compound in the form of a barcode, for example it may be a thread printed with an ink comprising a photochromic compound, the printing being under form of bars perpendicular to the longitudinal axis of the wire can also be provided

  that the printing is done in the form of alphanumeric characters.

  When electromagnetic radiation is applied to such a wire

  initially colorless, readable impressions will appear.

  One embodiment of the invention may be to use mixtures of photochromic compounds or different photochromic compounds for certain parts of the security element, these compounds giving different colors for a given radiation or reacting to radiation of lengths. different waves. The photochromic compound (s) can be incorporated into the bulk safety element or deposited on the surface at

  least one face of the element, for example by coating or printing.

  The electromagnetic radiation to which the security document according to the invention is subjected is preferably a visible light whose spectrum of wavelength corresponds to that of the spectrum

solar.

  The security document is preferably obtained by wet process by producing an aqueous suspension of a mixture of natural and / or synthetic and / or mineral fibers, binders, flocculants and then draining this suspension on a fabric, for example a flat table of a fourdrinier machine or a canvas of a round shape and

  finally pressing and drying the resulting sheet.

  The following description with reference to the nonlimiting examples

  below will help understand how the invention can be put

in practice.

EXAMPLES

Example 1

  A mixture of polycarbonate and a photochromic compound of the spiro (or naphtho) pyran type having, as substituent, an adamantane ring at the 2-position of the spiropyran ring (as described in the patent application EP-A-246 114) is extruded. Biaxially stretched The film is obtained until a film of thickness of μm is obtained. A colorless film is obtained. This film is cut into strips 1 mm wide. The strip is incorporated in a sheet of paper according to the technique described in the patent application. EP-A-059 056 The sheet obtained is cut to make

security documents.

  If we illuminate the security document obtained according to the invention in full sunlight, the security document becomes very dark immediately As soon as we put the security document in a place

  less enlightened, the security document clears up very quickly.

Example 2

  A security document is produced as in Example 1, but a polymethacrylate is used in place of the polycarbonate and, as a photochromic, a stabilized spiroxazine resistant to

  fatigue, as described in patent application FR-A-2 523 593.

Example 3

  A paper of 38 g / m 2 is printed with helicoid photochromic ink containing a spiroindolinonaphtoxazine. This paper is cut in the form of boards. These boards are introduced into a sheet of paper during its manufacture and in such a way as to obtain a finished sheet comprising a large amount of paper. quantity of boards flush with the sides of the sheet This sheet is transformed into security documents. By irradiation of a document obtained at a wavelength of 366

  nanometers, the security elements are quickly colored in blue.

  They get discolored very quickly if you put the document in a

non-irradiated place.

Example 4

  A security document is produced by incorporating, during its manufacture, photochromic organic fibers, for example polyamide fibers (NYLON) described in US Pat. No. 3,578,389. When exposing the document obtained, in full sunlight, the photochromic fibers flush with one of the sides of the document, change from orange to blue.

Example 5

  A security document is produced as in Example 4, but the photochromic fibers used are mineral glass fibers having a high content of zirconia and the photochromic compound of which is a silver halide with copper oxide. Zirconia increases the speed of photochromic reversibility Photochromic fibers can for example be obtained from glass

  minerals described in the patent application FR-A-2,290,401.

Claims (4)

  A non-woven security document comprising integrally at least one security element comprising at least one photochromic compound reacting reversibly to electromagnetic radiation reaching it and whose wavelength spectrum corresponds to that of the solar spectrum, in a period of   less than 1 minute, for several cycles.   Safety document according to Claim 1, characterized in that the photochromic compound is resistant to a temperature up to 120 OC.   Security document according to one of claims 1 and 2,   characterized in that the photochromic compound is chemically resistant to oxidizing and / or reducing agents and / or the bases and / or acids.   Security document according to one of the preceding claims,   characterized by the fact that the security element is disposed at   less partially between its two faces.   Security document according to one of the preceding claims,   characterized in that the security element is completely enclosed between the two sides of the document, and located at a depth   allowing the electromagnetic radiation to reach him.