Photosensitive optically variable ink compositions useful for ink jet printing
First Claim
1. An aqueous ink capable of producing dark, machine-readable markings 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 emitting light within a characteristic emission band when excited by fluorescent-exciting radiation;
(b) a second colorant comprising a blue colloidal pigment alone or with a dye, the second colorant having a light absorption band at longer wavelengths than the characteristic emission band of the first colorant or overlapping the emission wavelength of the first colorant, effectively 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.
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Accused Products
Abstract
New photosensitive optically variable inks are capable of printing images having improved resistance to water. The inks produce images which can be viewed with both visible and ultraviolet light to have physically coincident positive and negative images. They contain at least two types of colorants and other suitable ingredients to enable preparation for printing. The first colorant comprises a fluorescent dye emitting light within a characteristic emission band when excited by fluorescent-exciting radiation. The second colorant, which comprises a colloidal pigment alone or with a dye, has a light absorption band at longer wavelengths than the characteristic emission band of the first colorant or overlapping the emission wavelength of the first colorant, effectively to result in a dark color. The composition also contains 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.
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Citations
17 Claims
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1. An aqueous ink capable of producing dark, machine-readable markings 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 emitting light within a characteristic emission band when excited by fluorescent-exciting radiation; (b) a second colorant comprising a blue colloidal pigment alone or with a dye, the second colorant having a light absorption band at longer wavelengths than the characteristic emission band of the first colorant or overlapping the emission wavelength of the first colorant, effectively 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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8. An aqueous ink capable of producing dark, machine-readable markings 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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(d) a first colorant comprising a fluorescent dye emitting light within a characteristic emission band when excited by fluorescent-exciting radiation; (e) a second colorant comprising a blue colloidal pigment alone or with a dye, the second colorant having a light absorption band at longer wavelengths than the characteristic emission band of the first colorant or overlapping the emission wavelength of the first colorant, effectively to result in a dark color, preferably black, and (f) an aqueous liquid vehicle comprising water, a water soluble resin, 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; said ink exhibiting waterfastness Reflectance Ratio values of greater than 2 and Red Modulation values of greater than 0.65, when measured by tests WF-1 and WF-2. - View Dependent Claims (9, 10, 11, 12)
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13. A process for printing a security marking comprising:
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providing an ink comprising (a) a first colorant comprising a fluorescent dye emitting light within a characteristic emission band when excited by fluorescent-exciting radiation, (b) a second colorant comprising a blue colloidal pigment alone or with a dye, the second colorant having a light absorption band at longer wavelengths than the characteristic emission band of the first colorant or overlapping the emission wavelength of the first colorant, effectively 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; printing an image with said ink. - View Dependent Claims (14, 15, 16, 17)
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Specification