Ink-jet printing paper with improved waterfastness

Ink-jet printing technology has experienced dramatic advances in the last decade, and is widely used in small businesses and home offices because of its excellent resolution, low price, and brilliant multicolor output. The ink-jet process involves two distinct parts, the inks and their application, and the media surface. Improvements in ink-jetting technology and the corresponding improvement in image application resolution have caused waterfastness to become more limiting to the achieved resolution. Our research work attempts to improve waterfastness by incorporating cationically modified boehmites into paper coating formulations that interact more strongly with anionic dyes in the inks. Boehmites (gamma-AlOOH) were surface-modified using commercially available [N,N,N-trimethyl]-ammonium propyl-(trimethoxy)-silane salts in nonaqueous reactions. The modified boehmites were characterized using infrared spectroscopy, thermogravimetric analysis, zeta potential, X-ray photoelectron spectroscopy, and pore size analysis to assess the extent of modification and pore size effects. Aqueous, high pigment volume concentration paper coatings were then formulated from the boehmites and applied to paper substrates to assess the relative ability of the coatings to retain printed image dyes. The coatings were characterized for dispersion viscosity and gloss, while printed images on the coatings were tested by water spot, fixed dye, and water drip analyses. Coatings synthesized using the surface-modified pigments showed a reduced binder demand as well as improved image waterfastness and fixed-dye adsorption properties as compared to the unmodified boehmite coatings.