| abstract |
A magnetic ink concentrate is described, consisting essentially of a dispersion of hard magnetic solid particles in water or alcohol in the presence of polyelectrolytes with a molecular weight between 1000 and 25000, selected from the group of polyacrylates, acrylic acid / acrylamide copolymers and polyvinylphosphonic acids and the alkali metal salts of these compounds with the proviso that the magnetic pigments have a specific surface area of 70 to 200 m 2 / g, a coercive force between 10 and 500 kA / m and a remanent magnetization of over 10 nTm 3 / g. Biodegradable polycondensates of organic hydroxycarboxylic acids, alcohols or acetals can also be used as polyelectrolytes. The magnetic ink concentrate can be produced very easily in one operation. |