On the Structure of Ink-Water Emulsions as Derived from Dielectric Constant Measurements

Some conclusions regarding the structure of ink/water emulsions have been derived from static and dynamic dielectric constant measurements of real and synthetic black ink and dampening solution mixtures. Mixtures without carbon black were also evaluated. Under static conditions, the results are consistent with carbon black dispersed as nonspherical agglomerates and dampening solution dispersed as a separate phase consisting of spherical particles. When shear stress is applied to ink mixtures by forced flow through a tube, the dielectric constant increases significantly. The increase is greater when the dampening solution content is large. This may be explained by deformation of the water droplets by the flow field. The carbon black agglomerates remain unaffected at the shear rates used in these experiments.