Blacks for Printing Inks

With a consumption of about 150 000 t/a carbon blacks are the most important pigments used in the printing-ink industry. The required properties of the pigment black vary rather widely, depending on the printing process and the type of binder. 

The chemical drying of printing inks involves oxidation (where unsaturated oils are cross-linked by atmospheric oxygen) or polymerization of binder constituents by UV light. The first setting is often by striking in, even with chemically-dried printing inks. 

Letterpress printing call for high-viscosity inks (5-50 Pa s) that do not run over the edges of the types. 

Flexographic printing inks are similar to those used in gravure processes but have a somewhat higher carbon black concentration (10-15%). 

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