Pigment printing pastes

Although the products needed for the production of pigment printing pastes are marketed under the trade names of various manufacturers, very few differences in their basic composition are worthy of mention. The results obtained from the various systems may differ, however, especially from the viewpoint of problem-free printing properties, fastness properties, evenness, brilliance and handle of the goods.

Pigment printing pastes

The ratio of the amount of pigment paste to binder necessary to produce good fastness properties is influenced by the fact that even the smallest amount of pigment (perhaps 1 g pigment paste per kg paste) requires a layer of binding film at least 5 µm thick. Including a safety factor, this means a minimum of about 7% binder (of about 40% solid content) in the paste. Additional pigment needs about 1.5–2 times its own mass of binding substance.

 The relation shown in Recipe 5.1 results. For prints on hydrophobic materials (including polyester/cotton blends), another 0.5–1% of external crosslinking agent is added to the paste, depending on the colour depth and the desired wash fastness. The reduction thickener contains 8% binder, and other components as listed in Table 5.1. Often several components (emulsifier, printing concentrate, crosslinking agent, softener and flow moderator) are combined in one product by the product manufacturers, which means that the recipe is simpler but also that there is not the same amount of flexibility with respect to optimum printing recipes.