Stability study of nanopigment dispersions

The use of organic pigments rather than dyes for printing ink applications in aqueous systems gives an adequate response in terms of image durability. The main issue with pigments for printing applications is the low stability of their suspensions. Due to the hydrophobic character or high surface energy of the particles, they tend to aggregate into bigger particles with eventual settling. In this paper we present a study of particles size, zeta potential, absorbance and other properties of suspensions prepared with hybrid (intercalated dye-clay) pigment. A stability study was carried out by an encapsulation with anionic PSS poly (sodium 4-styrenesulfonate) and cationic PDADMAC Poly (diallyldimethylammonium-chloride) polyelectrolytes to improve the stability of the pigment particle suspensions. Preliminary studies indicate that improved stability of suspensions of pigment can be achieved by coating with a layer of PDADMAC.