(12) United States Patent ao) Patent No.: Us 7,192,474 B2
Auslander et al. (45) Date of Patent: *Mar. 20,2007
(54) IR ABSORBING PHOTOSENSITIVE OPTICALLY VARIABLE INK COMPOSITIONS AND PROCESS
(75) Inventors: Judith D. Auslander, Westport, CT (US); Mike Y. R. Chen, Shelton, CT (US)
(73) Assignee: Pitney Bowes Inc., Stamford, CT (US)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 77 days.
This patent is subject to a terminal disclaimer.
(21) Appl. No.: 10/873,320
(22) Filed: Jun. 22, 2004
(65) Prior Publication Data
US 2005/0279247 Al Dec. 22, 2005
(51) Int. CI.
C09D 11/02 (2006.01)
(52) U.S. CI 106/31.32; 106/31.64;
(58) Field of Classification Search 106/31.32,
106/31.64, 31.28 See application file for complete search history.
(56) References Cited
U.S. PATENT DOCUMENTS
Water-soluble, photosensitive, optically variable (POV) inks exhibit improved OCR readability due to improved infrared absorption properties. The inks can produce images that can be viewed with both visible and ultraviolet light to have physically coincident positive and negative images. The new inks contain at least two types of colorants in addition to the IR absorber and other suitable ingredients. The first colorant comprises a fluorescent dye or pigment emitting light within a characteristic emission band when excited by fluorescentexciting radiation. The second colorant comprises a carbon black infrared radiation absorbing composition alone or with one or more dyes or pigments having a light absorption band at longer wavelengths than the characteristic emission band of the first colorant or also overlapping the emission wavelength of the first colorant in such a way as to result in a dark color. The inks are formulated to provide higher contrast in the presence of IR radiation while retaining a strong negative correlation between the visible and fluorescent images.
7 Claims, 5 Drawing Sheets