Relationship between the dye/additive interaction and inkjet ink droplet formation

To design adequate ink composition for textile printing, the relationship between the dye/additive interaction and ink performance is investigated. In the present study, the three acid dyes C. I. Acid Red 88, 13, and 27, a water-soluble polymer poly(vinylpyrrolidone) (PVP) and three surfactants, sodium dodecyl sulfate (SDS), octaethylene glycol monododecyl ether (OGDE), and Surfynol 465 (S465) were used and the dye/additive interaction was investigated by means of visible absorption measurements. The visible absorption spectra of aqueous dye solutions changed with the addition of the nonionic surfactants, but further addition of PVP had little effect on the spectra, indicating that the strong binding of the dye molecules with the nonionic surfactant micelles is maintained even in the presence of PVP. In contrast, in the case of SDS, the spectra changed with the addition of the surfactant as well as with further addition of PVP. This indicates that the behavior of the acid dyes in the three-species system depends on the dye structure, the surfactant structure, and the molecular weight of PVP. Furthermore, to estimate the ink performance, the physical properties of the ink, such as viscosity, surface tension, and ink droplet formation were determined. Ink solutions with favorable physicochemical properties and low molecular weight PVP showed good ink droplet formation. In the optimized ink composition (PVP-1/S465: 1.4/0.004 mol dm−3) most of the dye molecules are strongly bound to the PVP chain, but the binding is not significantly affected by the addition of S465.

► The relationship between dye/additive interaction and ink performance is investigated.
► The interaction depends on chemical structure of dyes, polymer and surfactants.
► The composition of the ink solution having excellent ink droplet formation was observed.
► Lower molecular weight of polymer also appropriate in the ink droplet formation.
► In the ink, all dye molecules are bound to the polymer chains.