Ink set, printed article, a method of printing and use of a colorant

• US 20040253419A1
• Filed: 04/14/2004
• Published: 12/16/2004
• Est. Priority Date: 10/31/2001
• Status: Active Grant

• Current Assignee: Sicpa Holding SA
• Original Assignee: Sicpa Holding SA
• Inventors: Muller, Edgar, Despland, Claude-Alain, Bleikolm, Anton, DeGott, Pierre
• Granted Patent: US 6,926,764 B2
• Time in Patent Office: Days
• US Class Current: 428/195.1
• CPC Class Codes: B41M 3/14 Security printing securities B42D25/29
• CPC Class Codes: C09B 47/08 Preparation from other phthalocyanine compounds , e.g. cobaltphthalocyanineamine complex
• CPC Class Codes: C09B 47/20 Obtaining compounds having sulfur atoms directly bound to the phthalocyanine skeleton
• CPC Class Codes: C09D 11/40 Ink-sets specially adapted for multi-colour inkjet printing
• CPC Class Codes: Y10T 428/24802 Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]

Abstract

The invention relates to an ink set comprising a plurality of inks of a first and of a second group, having different colors. Inks of said first group comprise a visible colorant and an additional IR-absorbing compound (IR-taggant) which has an absorption peak at a predetermined wavelength in the near infrared. Inks of said second group comprise a visible colorant which has at the same time an infrared absorption peak at the same wavelength as that of the IR-taggant used in the inks of the first group. Preferred embodiment is a four-color process ink set comprising an IR feature.

Claims

1-15. -15. (Cancelled).

16. An ink set for printing light absorbing indicia comprising at least two inks, each of said inks having at least one colorant, pigment or dye absorbing visible light,

wherein the ink set has a first group of inks and a second group of inks,

the inks of said first group including an additional taggant with a predetermined spectral characteristic, and

the inks of said second group having a colorant, dye or pigment with a spectral characteristic.

17. An ink set according to claim 16, wherein said predetermined spectral characteristic of said additional taggant is an absorption characteristic.

18. An ink set according to claim 16, wherein said spectral characteristic of said colorant, dye or pigment in the inks of said second group is an absorption characteristic at least partially similar to the spectral characteristic of said taggant.

19. An ink set according to claim 16, wherein the colorant, dye or pigment of the inks of the second group have a NIR absorption peak, at a wavelength substantially identical to the wavelength of a NIR absorption peak of the taggant of the inks of the first group.

20. An ink set according to claim 16, wherein the ink set consists of a black, a yellow, a magenta and a cyan ink.

21. An ink set according to claim 16, wherein the first group of inks includes black, yellow and magenta inks and wherein the second group of inks includes cyan or green inks.

22. An ink set according to claim 16, wherein the colorant of the ink of the second group is a phthalocyanine.

23. An ink set according to claim 22, wherein said phthalocyanine is a metal free unsubstituted dihydrogeno phthalocyanine of the crystallographic X-form.

24. An ink set according to claim 16, wherein the taggant has an absorption peak in the wavelength range of 700 nm to 900 nm.

25. An ink set according to claim 24, wherein said absorption peak is at a wavelength of 780 nm.

26. An ink set according to claim 24, wherein the colorant of the second group of inks has an absorption peak in the wavelength range between 700 nm and 900 nm.

27. An ink set according to claim 26, wherein said absorption peak is at a wavelength of 780 nm.

28. An ink set according to claim 16, wherein the taggant is a benzenethiol-substituted copper phthalocyanine.

29. An ink set according to claim 16, wherein the taggant has substantially no absorption in the visible spectrum.

30. An ink set according to claim 16, wherein said taggant has a light fastness of at least 3 on the international wool scale.

31. An ink set according to claim 16, wherein said colorant, dye or pigment has a light fastness of at least 3 on the international wool scale.

37. A dual ink set comprising a conventional four-colors ink set and an ink set according to claim 16.

32. A printed article carrying a light-absorbing indicia, the indicia being printed with an ink set comprising at least two inks,

each of said inks having at least one colorant, dye or pigment,

wherein the ink set has a first group of inks and a second group of inks,

the inks of said first group including an additional taggant with a predetermined spectral characteristic, and

the inks of said second group having a colorant, dye or pigment with a spectral characteristic at least partially similar to the spectral characteristic of said taggant.

33. A printed article according to claim 32, wherein said ink set is an ink set comprising at least two inks,

each of said inks having at least one colorant, pigment or dye absorbing visible light,

wherein the ink set has a first group of inks and a second group of inks,

the inks of said first group including an additional taggant with a predetermined spectral characteristic, and

the inks of said second group having a colorant, dye or pigment with a spectral characteristic.

34. A printed article according to claim 32, wherein said predetermined spectral characteristic of said additional taggant is an absorption characteristic.

35. A method of printing an indicia having a predetermined spectral characteristic onto an article, the method comprising the steps of

applying at least one ink having a predetermined colorant of a first group of inks and

applying at least one ink of a second group of inks having a different color than the inks of the first group

wherein the inks of said first group include an additional taggant with a predetermined spectral characteristic and

wherein the inks of the second group have a colorant with a spectral characteristic at least partially similar to the absorption characteristic of said taggant.

36. The method according to claim 35, wherein said method is carried out with an ink set comprising at least two inks,

each of said inks having at least one colorant, pigment or dye absorbing visible light,

wherein the ink set has a first group of inks and a second group of inks,

the inks of said first group including an additional taggant with a predetermined spectral characteristic, and

the inks of said second group having a colorant, dye or pigment with a spectral characteristic.