PREPARATION OF MAGNETIC INKS - ADSORPTION OF MACROMOLECULAR DISPERSION AGENTS ON MAGNETIC METALLIC IRON PIGMENTS AND ELECTRICAL CHARGE FORMATION

The interaction between metallic iron pigments (MPs) and the actual co nstituents of magnetic ink is examined by first determining the adsorp tion isotherms and analyzing by FTIR the type of bonding that is estab lished between the constituents and MP. Then, following the approach d escribed in a previous paper using model compounds, the formation of e lectrical charges on MPs is examined through acoustophorometric (Elect rokinetic amplitude or ESA) measurements. It is shown that the variati on in ESA is related to charge transfer processes and reflects the MP- constituent interactions, Finally, adsorption competitions are shown a nd the importance of the method of preparation (order of mixing of lth e ingredients of the ink) is illustrated. (C) 1997 Academic Press.