Effect of sodium N-lauroylsarcosinate/hypromellose on the dispersibility and rheological behavior of carbon black for paper coating application

The dispersibility of the carbon black (CB) in aqueous phase is rather critical for its application in paper coatings . In the present work, sodium N-lauroylsarcosinate/hypromellose (HPMC) was developed/prepared via hydrated reaction, which was subsequently used as a dispersant for improving the dispersibility of CB dispersion. The effects of the as-prepared dispersant on the dispersibility and rheological behavior of the CB dispersion were systematically studied, and the microstructure and properties of the CB dispersion were comprehensively characterized. The results showed that the presence of dispersant could reduce the viscosity and enhance the zeta potential of the CB dispersion. Compared with the CB dispersion without dispersant, the viscosity of CB dispersion with 4.0 wt% dispersant was decreased by 7.3%, and the zeta potential was increased by 167%. The average particle size and adsorption capacity of CB dispersion with 4.0 wt% dispersant retained 190 nm and 3351 mg/g, respectively. With the increase of dispersant amount, the dynamic viscoelasticity was gradually increased. It was further inferred that sodium N-lauroylsarcosinate part increased the electrostatic repulsion between CB particles, and the HPMC part particularly enhanced the steric hindrance. These two parts could produce a positive synergistic dispersion effect and made the CB dispersion more stable.