EP0327788A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Reversibly photochromic printing inks
Assignee: SICPA Holding SA
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Filing: 1988-12-21
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Granted: —
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Expires: 2008-12-21
Abstract
Abstract Photochromic printing inks are disclosed which are in particular used for the printing of security documents. Prints are normally nearly colorless and become colored when energy irradiated, such as by ultraviolet light. This photocoloration is reversible. The printing inks contain photochromic compounds which are protected against oxygen and other ink components. Methods are described to prepare the inks, to print security documents, and to detect counterfeiting.
Inventors
- 👤 Albert Amon
- 👤 Haim Bretler
- 👤 Anton Bleikolm
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 08:07
CPC Classifications
C; C09; C09D; C09D11/00; C09D11/50; B; B41; B41M; B41M3/00; B41M3/14; B41M3/142; G; G03; G03C; G03C1/00; G03C1/685
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
62 words
A photochromic printing ink for the printing of ink accepting surfaces, said ink containing a polymeric binder, a liquid phase, and at least one photochromic compound being surrounded by a light-transparent, polymeric protecting composition inert to said photochromic compound and being a barrier for oxygen and for ink components capable of irreversibly interfering with the photochromic reaction sites of said photochromic compound.
Claim 2
Dependent Claim
62 words
A photochromic printing ink for the printing of ink accepting surfaces, said ink containing a polymeric binder, a liquid phase, and at least one photochromic compound being surrounded by a light-transparent, polymeric protecting composition inert to said photochromic compound and being a barrier for oxygen and for ink components capable of irreversibly interfering with the photochromic reaction sites of said photochromic compound.
Claim 3
Dependent Claim
24 words
The photochromic printing ink of claim 1 wherein said photochromic compound is selected from the classes comprising spiro-indolino-naphthoxazines, spirobenzopyrans, spirobenzothiopyrans, spironaphtothiopyrans and their derivatives.
Claim 4
Dependent Claim
20 words
The photochromic printing ink of claim 1 wherein said photochromic compound is selected from the class comprising fulgides and fulgimides.
Claim 5
Dependent Claim
18 words
The photochromic printing ink of claim 1 wherein said photochromic compound is selected from the class comprising spiro(1,8a)-dihydroindolizines.
Claim 6
Dependent Claim
26 words
The photochromic printing ink of claim 1 wherein the said polymeric protecting composition is selected from thermoplastic polymers which are not attacked by said liquid phase.
Claim 7
Dependent Claim
32 words
The photochromic printing ink of claim 5 wherein said photochromic compound is contained as a solid solution in a particulate thermoplastic polymer having a particle size of from 1 to 20 micrometers.
Claim 8
Dependent Claim
24 words
The photochromic printing ink of claim 1 wherein said photochromic compound is contained in microcapsules having a size of from 1 to 20 micrometers.
Claim 9
Dependent Claim
116 words
A photochromic printing ink for the printing of ink accepting surfaces, said ink containing a polymeric binder or a binder prepolymer curable to said polymeric binder, a liquid phase, and at least one photochromic compound, said ink being free from binder curing systems based on ionic mechanisms, said polymeric binder and any other component of said ink being free from functional groups interferring irreversibly with the photochromic reactions of said photochromic compound involved in photocoloration, said polymeric binder or prepolymer being further selected from light-transparent compositions acceptable for printing inks, being a barrier for oxygen, and being capable of permanently solubilizing said photochromic compound with the appropriate concentration in the liquid ink and the dried prints.
Claim 10
Dependent Claim
116 words
A photochromic printing ink for the printing of ink accepting surfaces, said ink containing a polymeric binder or a binder prepolymer curable to said polymeric binder, a liquid phase, and at least one photochromic compound, said ink being free from binder curing systems based on ionic mechanisms, said polymeric binder and any other component of said ink being free from functional groups interferring irreversibly with the photochromic reactions of said photochromic compound involved in photocoloration, said polymeric binder or prepolymer being further selected from light-transparent compositions acceptable for printing inks, being a barrier for oxygen, and being capable of permanently solubilizing said photochromic compound with the appropriate concentration in the liquid ink and the dried prints.
Claim 11
Dependent Claim
22 words
The photochromic printing ink of claim 8 wherein the polymeric binder or its prepolymers are free from carboxyl groups and their salts.
Claim 12
Dependent Claim
27 words
The photochromic printing ink of claim 8 wherein the polymeric binder is selected from compositions being compatible with hydrocarbon solvents and having an acid number below 10.
Claim 13
Independent Claim
175 words
A method for preparing a photochromic printing ink for the printing of ink accepting surfaces, comprising the following steps: (A) providing at least one photochromic compound and a thermoplastic, light-transparent polymer not reactive with said photochromic compound and being a barrier for oxygen and for ink components capable of irreversibly interferring with the photochromic reaction sites of said photochromic compound, (B) melting together said photochromic compound and said polymer at a temperature comprised between 50°C and 150°C to form a liquid solution or dispersion of the photochromic compound within the polymer, (C) allowing said liquid solution or dispersion to cool to ambient temperature to form a solid solution or dispersion, (D) breaking up the solid mass obtained in step (C) to lumps and micronizing the lumps to particles having a size of from 1 to 20 micrometers, (E) incorporating the particles obtained in step (D) into a printing ink formulation, and (F) collecting the obtained ink comprising a particulate polymeric binder, a liquid phase, and at least one photochromic compound, embedded in said polymeric binder.
Claim 14
Independent Claim
175 words
A method for preparing a photochromic printing ink for the printing of ink accepting surfaces, comprising the following steps: (A) providing at least one photochromic compound and a thermoplastic, light-transparent polymer not reactive with said photochromic compound and being a barrier for oxygen and for ink components capable of irreversibly interferring with the photochromic reaction sites of said photochromic compound, (B) melting together said photochromic compound and said polymer at a temperature comprised between 50°C and 150°C to form a liquid solution or dispersion of the photochromic compound within the polymer, (C) allowing said liquid solution or dispersion to cool to ambient temperature to form a solid solution or dispersion, (D) breaking up the solid mass obtained in step (C) to lumps and micronizing the lumps to particles having a size of from 1 to 20 micrometers, (E) incorporating the particles obtained in step (D) into a printing ink formulation, and (F) collecting the obtained ink comprising a particulate polymeric binder, a liquid phase, and at least one photochromic compound, embedded in said polymeric binder.
Claim 15
Dependent Claim
23 words
The method of claim 11 wherein an inert solvent for the polymer is added in step (B) and stripped off in step (C).
Claim 16
Independent Claim
108 words
The method for preparing a photochromic printing ink for the printing of ink accepting surfaces, comprising encapsulating at least one photochromic compound by the process of coacervation into microcapsules having a size of from 1 to 20 micrometers, the shell of said microcapsules being formed by a light-transparent, polymeric protecting composition inert to said photochromic compound and being a barrier for oxygen and for ink components capable of irreversibly interfering with the photochromic reaction sites of said photochromic compound, incorporating the microcapsules so obtained into a printing ink formulation, and collecting the obtained ink comprising a polymeric binder, a liquid phase, and at least one encapsulated photochromic compound.
Claim 17
Independent Claim
108 words
The method for preparing a photochromic printing ink for the printing of ink accepting surfaces, comprising encapsulating at least one photochromic compound by the process of coacervation into microcapsules having a size of from 1 to 20 micrometers, the shell of said microcapsules being formed by a light-transparent, polymeric protecting composition inert to said photochromic compound and being a barrier for oxygen and for ink components capable of irreversibly interfering with the photochromic reaction sites of said photochromic compound, incorporating the microcapsules so obtained into a printing ink formulation, and collecting the obtained ink comprising a polymeric binder, a liquid phase, and at least one encapsulated photochromic compound.
Claim 18
Independent Claim
147 words
A method for preparing a photochromic printing ink for the printing of ink accepting surfaces comprising the following steps: (A) providing a polymeric binder or a binder prepolymer curable to said polymeric binder by a free radical induced reaction mechanism, (B) providing additional printing ink components including liquids, said binder or said prepolymer and said additional components being selected to be free from functional groups irreversibly interferring with photochromic reactions of said photochromic compound involved in photocoloration, said polymeric binder or binder prepolymer being further selected from light-transparent compositions acceptable for printing inks, being a barrier for oxygen, and being capable of permanently solubilizing said photochromic compound with the appropriate concentration in the liquid ink and the dried prints, and (C) blending said ingredients and collecting a photochromic printing ink comprising a polymeric binder or a binder prepolymer, a liquid phase, and at least one photochromic compound.
Claim 19
Independent Claim
147 words
A method for preparing a photochromic printing ink for the printing of ink accepting surfaces comprising the following steps: (A) providing a polymeric binder or a binder prepolymer curable to said polymeric binder by a free radical induced reaction mechanism, (B) providing additional printing ink components including liquids, said binder or said prepolymer and said additional components being selected to be free from functional groups irreversibly interferring with photochromic reactions of said photochromic compound involved in photocoloration, said polymeric binder or binder prepolymer being further selected from light-transparent compositions acceptable for printing inks, being a barrier for oxygen, and being capable of permanently solubilizing said photochromic compound with the appropriate concentration in the liquid ink and the dried prints, and (C) blending said ingredients and collecting a photochromic printing ink comprising a polymeric binder or a binder prepolymer, a liquid phase, and at least one photochromic compound.
Claim 20
Dependent Claim
20 words
The method of claim 14 wherein said binder or said prepolymer are selected free from carboxyl groups and their salts.
Claim 21
Dependent Claim
24 words
The method of claim 14 wherein said binder is selected from compositions being compatible with hydrocarbon solvents and having an acid number below 10.
Claim 22
Dependent Claim
16 words
The method of claim 14 which said binder prepolymer is curable on irradiation with ultraviolet light.
Claim 23
Independent Claim
89 words
A method for the printing of security documents, comprising the following steps: (A) selecting a photochromic printing ink of any one of claims 1 to 10, (B) selecting a non-photochromic printing ink, (C) printing with these inks simultaneously or in the course of the same printing procedure a flat substrate accepting the inks of steps (A) and (B), according to predetermined patterns, (D) drying the print or prints obtained in step (C), and (E) collecting a printed security document showing photochromic lines or patterns and non-photochromic lines and patterns.
Claim 24
Dependent Claim
43 words
The method of claim 18 comprising mixing the printing inks of steps (A) and (B) and collecting in step (E) a printed security document showing photochromic lines or patterns where the printed color reversibly changes by photochromism under energy radiation to another color.
References Cited (Backward Citations)
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