Photo-induced crashing of ink-jet ink compositions

A method of printing an image on a substrate with increased print quality, water and smear fastness, and optical density, comprising:

• a) formulating an ink-jettable ink composition, comprising:
• i) an effective amount of an ink vehicle,
• ii) an effective amount of an ink colorant having solubility properties that are pH dependent, and
• iii) an effective amount of a photo-initiated acid generator;
• b) jetting said ink composition from an ink-jet pen onto a substrate;
• and
• c) exposing said ink-jetted ink on said substrate to radiation wherein said ink-jet ink composition exhibits reduced pH, followed by precipitation of the colorant.

A system for printing an image on a substrate with increased ink efficiency, comprising:

• a) an ink-jet ink pen containing an ink-jettable ink composition, comprising:
• i) an effective amount of an ink vehicle,
• ii) an effective amount of an ink colorant having solubility properties that are pH dependent, and
• iii) an effective amount of a photo-initiated acid generator, wherein said composition exhibits a decrease in pH upon exposure to radiation, followed by precipitation of the ink colorant;
• b) a substrate configured for accepting a printed image from said ink-jet pen;
• and
• c) an energy source configured for irradiating said printed image such that a decrease in pH is realized resulting in precipitation of the ink colorant.