SYNOPSIS
Butyl-substituted naphthalenesulfonate formaldehyde condensates (C4NSF) with different molecular weights were synthesized. The structures were confirmed by NMR in terms of the appearance of the signal at 6 = 3.3-4.0 ppm, and the molecular weights of the synthesized C4NSFs were compared by gel permeation chromatography (GPC ) . C4NSFs used as dispersants were compared to unmodified naphthalenesulfonate formaldehyde condensates (NSF) in their ability to disperse nonpolar particles (carbon black) and polar particles (TiO,) in water. Their dispersing ability was evaluated by both a viscosity method and a microscopy method. For dispersing carbon black in water, it was found that using C4NSFs as dispersing agents results in a lower viscosity, a lower yield value by the viscosity method, and a more homogeneous dispersion of particles as determined by microscopy. These results indicate that the butyl group enhances the dispersing ability of C4NSF. The effect of the butyl group on the dispersing ability of C4NSF was interpreted by the results of the measured adsorption amount that was also enhanced by the existence of the butyl group. For dispersing TiO, in water, C4NSF results in a higher viscosity and a higher adsorption amount of the dispersed system than NSF. These phenomena were interpreted in terms of the hydrophobic interaction between the butyl groups and the bridging effect.