Functional polymers for colloidal application. IX. The dispersing ability of anionic and zwitterionic aniline‐formaldehyde condensates to dyes

Abstract

AbstractAnionic and zwitterionic aniline–formaldehyde condensates, N‐(3‐sodium propylsulfonate) aniline–formaldehyde condensates (PSAF), and N, N‐dimethyl‐N‐(3‐propylsulfonate) anilinium–formaldehyde condensates (DPSAF) are used as dispersants to disperse dyes (C. I. Navy Blue 79 and C. I. Brown 1), compared with the conventional dye dispersants–naphthalenesulfonate formaldehyde condensates (NSF). The dispersing properties of the condensates are assessed by the viscosity method, scanning electron microscopy (SEM), the final volume fraction after sedimentation, and adsorption behaviors. Compared to DPSAF, the PSAF and NSF with a lower molecular weight (PSAF‐L, NSF‐L) show significantly lower apparent viscosities of the paste of Navy Blue 79. Comparing the results of the viscosity method with those of SEM and the final volume fraction after sedimentation, it can be concluded that a better‐dispersed paste displayed by SEM shows a lower viscosity and a smaller final volume fraction. The amount of NSF‐L adsorbed on Navy Blue 79 is significantly higher than that of PSAF‐L and DPSAF‐H. However, the sulfonate on PSAF‐L can be extended more deeply toward the bulk phase compared to that on NSF‐L so that PSAF‐L can result in a high effective thickness. These adsorption phenomena are used to interpret the dispersing ability. For Brown 1, the anionic dispersants can reach a similar minimum viscosity independent of their molecular weight, but the PSAF with high molecular weight shows a remarkably low optimum concentration (ca. 3% compared to PSAF‐L 9%, NSFs 5%). © 1993 John Wiley & Sons, Inc.