CHEMISTRY OF INKS

Chemistry of Inks

Inks can be a complex medium, composed of solvents, pigments, dyes, resins, lubricants, solubilizers, surfactants, particulate matter, fluorescers, and other materials. Solvents or carriers enable inks to be applied in the liquid state.

History of inks

The history of Chinese inks can be traced back to the 23rd century BC

The India ink used in ancient India since at least the 4th century BC

1,600 years ago, a popular ink recipe was created

In the 15th century, a new type of ink had to be developed in Europe

Ink types

Types of Printing inks

Pad printing inks

Screen printing inks

Pad printing inks have formulations comparable to screen printing inks. Pad printing inks are formulated for rapid solvent evaporation.

Screen printing inks are designed to resist rapid evaporation so that they don’t dry in the screen.

Inks can be distinguished according to the way curing takes place

• Air-curing inks
• Heat-curing inks
• Two-component inks
• UV-curing inks
• Oxygen-curing inks
• Sublimation inks

Air-curing inks – is designed not to be heat set and cure at normal air temperature after printing.

Heat-curing inks require elevated temperatures for curing. The use of these ink systems is limited by the high curing temperature that the plastic must be able to withstand.

Two-component inks have the big advantage that no volatile components evaporate during curing. Pot-life after mixing is however limited.

UV-curing inks are widely used for screen-printing. The curing process is fast and environmental problems are smaller than for solvent-based systems. Small changes in ambient conditions have little influence, which makes the printing process very stable.

UV-curing inks are widely used for screen-printing. The curing process is fast and environmental problems are smaller than for solvent-based systems. Small changes in ambient conditions have little influence, which makes the printing process very stable.

Sublimation inks are heated to a temperature of about 200ºC (392ºF) during the application process, so that dyes in the ink sublime and are absorbed by the polymer surface while they are in the gas state. Sublimation inks are in the solid state at ambient temperature, like a wax, and become fluid when raised to 80ºC (176ºF) in the ink reservoir