Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
  • D21H21/40—Agents facilitating proof of genuineness or preventing fraudulent alteration, e.g. for security paper
  • D21H21/44—Latent security elements, i.e. detectable or becoming apparent only by use of special verification or tampering devices or methods
  • D21H21/46—Elements suited for chemical verification or impeding chemical tampering, e.g. by use of eradicators
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
  • D21H21/40—Agents facilitating proof of genuineness or preventing fraudulent alteration, e.g. for security paper
  • D21H21/42—Ribbons or strips

Definitions

• the invention relates to security paper, in particular banknote paper.
• Papers are already known which include strips or threads consisting of a transparent film provided with a continuous metallic layer, for example aluminum deposited under vacuum on polyester. Such threads, when introduced into paper which is then printed, are barely seen by the public in reflected light and become much more apparent in transmitted light.
• the purpose of these wires is to prevent a counterfeiter, from a common paper, from imitating an authentic document, by printing on this paper a dark line on the surface. In this case of counterfeiting, there is no difference between the visibility of the line in reflection and in transparency.
• EP-A-279 880 describes a transparent wire comprising metallic micro-prints obtained for example by demetallizing areas not protected by varnish. The prints are barely visible by reflection and more visible by transparency using a magnifying device.
• the invention aims to provide a support comprising a security element betraying falsification.
• a printable security sheet comprising a security wire visible in transmitted light and having a certain color, this wire being such that by the action of solutions attacking the printing inks, it becomes colorless and therefore invisible.
• the wire would become colorless and the counterfeiter could not reproduce the coloring effect by transmitted light by passing a stroke of a colored pencil, because it would then obtain a colored line which would be seen in reflected light.
• the counterfeiter - after having erased the surface prints - would have a white paper comprising a colored security thread and he could reprint the surface of the paper to obtain a ticket not comprising no evidence of tampering.
• the invention therefore relates to a printable security sheet comprising at least one security element disposed at least partially between the faces of the sheet, said element being colored in transmitted light, the sheet being such that the security element consists of a support coated at least partially with a layer consisting of at least one binder degradable in basic medium and at least one dye sensitive to bases, the binder being a means of protecting the dye in non-alkaline medium.
• the security element is a wire, but it can also be in the form of confetti or boards, strips, etc.
• the support is transparent. It can be made of polyester.
• the binder is degradable in basic medium, this means that it is degradable at pH greater than 8, preferably 10. However, it is not degradable at the pH of the aqueous suspension of fibers from which the sheet is formed.
• the binder according to the invention swells and becomes porous in the presence of an alkaline aqueous solution to allow the dye to diffuse out of the security element and / or its destruction.
• the binder can for example be chosen from homo-or copolymers with a high acid index, for example copolymers of (meth) acrylic ester, copoplymers of phthalic acid ester.
• the dyes are soluble in an acid medium and have no affinity for cellulose.
• the dyes can for example, in basic medium, have a colorless and soluble structure. They can split in alkaline medium into precursors, at least one of which is soluble. They can also become colorless in basic medium by redox reactions within the binder.
• the dye can be an organic amine salt, an eosin derivative, a triphenylmethane derivative.
• the dye can also be a combination of a dye precursor with a Lewis acid or a mixture of a triphenylmethane derivative with a reducing agent.
• a polyester film 23 micrometers thick is printed with an ink of the following composition (parts by dry weight): - A copolymer binder of acrylic ester sold under the name MOWILITH by HOESCHT which is dissolved in 10% in a 50/50 mixture by volume of methyl ethyl ketone and ethyl acetate. .... 97 games - a dye which is a solution of Malachite green sold by BAYER, at 2% in dimethylformamide. .... 3 parts
• the wire thus printed is dried. It is cut in the form of a wire.
• An aqueous suspension of cellulose fibers, optionally synthetic fibers, optionally fillers, optionally bonding agents is formed.
• the suspension is placed on a flat table on a Fourdinier machine or on a round form.
• the wire is introduced simultaneously into the suspension, in a known manner.
• the wire can be introduced completely into the heart of the paper or can come out superficially in certain places. We obtain a paper with a thread visible to the naked eye, green in color. If the paper is washed with a 2% aqueous sodium hydroxide solution for about an hour and a half, the green color disappears.
• a 23 micrometer polyester film is printed with an ink having the following composition: - a binder according to Example 1 .... 99 games - a dye which is a solution of precursor of red dye 6 B sold by CIBA, and of 2-4 dihydroxy-benzophenone in methyl ethyl ketone. .... 1 part
• the film is dried and cut into strips which are introduced into the paper.
• a paper is obtained comprising a thread visible to the naked eye, red in transparency. If the paper is washed with the same aqueous sodium hydroxide solution for about an hour and a half, the red color disappears.

Landscapes

• Paper (AREA)
• Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)
• Printing Methods (AREA)
• Credit Cards Or The Like (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=9387388

Family Applications (1)

Country Status (4)

Cited By (1)

Families Citing this family (1)

Citations (4)

Family Cites Families (1)

• 1989
  • 1989-11-14 FR FR8914926A patent/FR2654445B1/fr not_active Expired - Fee Related
• 1990
  • 1990-11-13 EP EP90403206A patent/EP0428447B1/de not_active Expired - Lifetime
  • 1990-11-13 DE DE69011816T patent/DE69011816T2/de not_active Expired - Fee Related
  • 1990-11-13 AT AT90403206T patent/ATE110430T1/de not_active IP Right Cessation

Patent Citations (4)

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