Characterization of Pigment Particle Surfaces by ToF-SIMS

The surface properties of pigment particles affect the flow behavior of coating colors and contribute to the chemistry and consolidation of the coating layer. It can also be hypothesized that chemical and morphological properties of pigment particles will contribute to printability at molecular level. Among the surface analytical techniques available, Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) has unique capabilities of combining detailed chemical and morphological information. Utilization of ToF-SIMS is still a reasonably new method for the analysis of paper surfaces and coating pigments. In this work we have used ToF-SIMS to investigate kaolin and calcium carbonate particles treated with dispersants. Characteristic secondary ions for pigments and dispersants were identified in the ToF-SIMS spectra. The lateral distribution of these ions was shown to be even at all dispersion levels, with slightly higher concentrations on edges of kaolin particles. Additive chemicals were detected on dispersed calcium carbonate surfaces. The normalized count of characteristic secondary ions for the components was compared with the dosage of polymer and differences in coverage of pigment surfaces could be detected. ToF-SIMS shows promise as a versatile tool for characterization of pigment particles and coating layers.