THE MECHANISM OF OFFSET INK PARTICLES AGGLOMERATION IN A CALCIUM FATTY-ACID COLLECTOR SYSTEM

Model studies on a dried ink particle suspension without fibres show t hat the kinetics of the ink agglomeration are totally dependent on the soap particle precipitation and formation. The calcium soap has to pr ecipitate before the ink and soap particles can agglomerate. Calcium i ons have two important effects on ink agglomeration: the precipitation of soap, and the reduction of the surface potential on the ink partic le surface. The importance of free fatty acid anions adsorbed onto the ink particle surface is negligible, since the fatty acid is almost co mpletely precipitated as calcium soap.