Interaction of resins and metal pigments in water‐borne printing inks Available to Purchase

In aqueous alkaline ink media aluminium pigments react with the evolution of hydrogen, whereas the more noble copper and brass pigments react by the absorption of oxygen, which can be measured gas‐volumetrically. These different corrosion reactions can be inhibited with addition of certain binders for printing inks, such as styrene‐maleic acid resins, maleic resins and to some extent styrene‐acrylate resins. So, certain ink resins inhibit corrosion reactions of different noble metal pigments in a reducing hydrogen atmosphere (aluminium) as well as in an oxidizing oxygen atmosphere (copper and brass). The overall best resin is that with the lowest acid number. Atomic absorption spectroscopy measurements showed that a lower acid number pruduces a lower solubility of copper and zinc in the medium.