Synthesis And Application Of Poly-carboxylic Dispersant For Pigment Ink-Jet Inks

Ink-jet ink is one of the most important factors in digital printing of textiles. Pigment ink is superior to dye ink in many properties, but the poor dispersing stability makes it difficult to be used. A poly-carboxylic dispersant was synthesized by solution polymerization method to improve the dispersing stability of pigment ink-jet inks.The factors such as the polymerization temperature, the dosage of initiator, the proportion of monomers were investigated. It was found that increasing the temperature and amount of initiator decreased the intrinsic viscosity of the copolymer. The synthesized copolymer was characterized by Fourier-Transform Infrared Spectroscopy(FT-IR), 13C Nuclear Magnetic Resonance Spectroscopy(13C NMR) and Gel Permeation Chromatography(GPC). The FT-IR spectrum showed that the copolymer consisted of styrene and maleic anhydride. The data of 13C NMR indicated that the polymer was a random copolymer of styrene and maleic anhydride arranged alternatively in the macromolecular chain. And the GPC indicated that the number-average molecular was 27,599 and the polydispersity was 2.35.The synthesis conditions of SMA influenced the dispersibility of the pigment ink-jet inks. When the temperature increased the dispersibility was improved. But increasing the initiator amount made the dispersibility increase to the max and then decreased. It was the same with increasing proportion of styrene and maleic anhydride. The addition of the third hydrophobic monomer resulted in the poor dispersibility.The more cycles that the pigment crushed, the smaller particle size and the better dispersibility were gotten. There were no more changes in the particle size and the dispersibility after the crushing cycles was 15 cycle. The increase of dispersant made particle size decreased and didn't influence viscosity before the pigment to dispersant was 4 to 1. The viscosity of the inks increased quickly after the pigment to dispersant higher 4 to 1. The dispersibility of the pigment ink increased stably with the additionof the dispersant. This result was also verified by the analysis of SEM.The addition of the diethylene glycol increased the viscosity, dispersibility but decreasing particle size. Fine dispersibility was obtained when the pH was 7-8. Comparing to ordinary dispersant, SMA was of better properties whatever in Zeta voltage, viscosity, particle size and dispersibility.