IR absorbing photosensitive optically variable ink compositions and process
First Claim
1. An aqueous ink capable of providing a secure marking including a dark, machine-readable image exhibiting fluorescence when exposed to fluorescent-exciting radiation, said ink being of suitable viscosity and surface tension for use in ink jet printing, comprising:
- (a) a first colorant comprising a fluorescent dye and/or pigment emitting light within a characteristic emission band when excited by fluorescent-exciting radiation;
(b) a second colorant comprising 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, preferably black, and (c) an aqueous liquid vehicle comprising water and a water-soluble vehicle in sufficient amounts to achieve an ink viscosity and surface tension effective for application of the ink to a substrate in a predetermined pattern by ink jet printing.
2 Assignments
0 Petitions
Accused Products
Abstract
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 fluorescent-exciting 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.
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Citations
7 Claims
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1. An aqueous ink capable of providing a secure marking including a dark, machine-readable image exhibiting fluorescence when exposed to fluorescent-exciting radiation, said ink being of suitable viscosity and surface tension for use in ink jet printing, comprising:
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(a) a first colorant comprising a fluorescent dye and/or pigment emitting light within a characteristic emission band when excited by fluorescent-exciting radiation;
(b) a second colorant comprising 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, preferably black, and (c) an aqueous liquid vehicle comprising water and a water-soluble vehicle in sufficient amounts to achieve an ink viscosity and surface tension effective for application of the ink to a substrate in a predetermined pattern by ink jet printing. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification