Determination of the colloidal stability of concentrated pigment dispersions
Yuan Yu, Richard Hall, and Ervina Halim¹; IS&T NIP23 International Conference on Digital Printing, 2007, Baltimore, MD, USA.
Abstract: Pigment dispersions are playing an increasingly important role in high performance inkjet inks. Colloidal stability of pigment particles can have a profound effect on print head and paper printing performance. Reliable and quick analytical methods to assess colloidal stability are essential in any development effort. Commonly accepted practice calls for aging the sample under accelerated conditions and then measuring the changes in particle size distribution. Widely applied particle sizing techniques require samples to be diluted. Dilution can disturb the system and the results may not reflect the concentrated state. In this report we explored the possibility of using an accelerated centrifugation method to evaluate colloidal stability without dilution. The instrument employed for this study is the LUMiFugeŽ. In this study, the colloidal stability of pigment dispersions as a function of pH and ionic strength were successfully determined without dilution or aging. Particularly intriguing, the LUMiFuge method can discern differences among samples that traditional methods fail to detect. This manuscript will also discuss the limitation of the LUMiFugeŽ. Our study strongly indicated that this is an extremely sensitive method to evaluate colloidal stability of dispersions at their original concentration. When LUMiFugeŽ results are correlated to the performance of pigmented inkjet inks, it can serve as a valuable tool for both research and development and quality control and assurance.
Key words: Polyelectrolyte stabilization • Dispersion stability • Silica • Centrifugation • Adsorption
¹ Inkjet Colorant Division, Cabot Corporation, 157 Concord Road, Billerica, MA 01821, USA.Contact us
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