Ultraviolet Curing and Dry Ink Printing

Ultraviolet curing (with relation to printing), more commonly referred to as just UV-curing , the process whereby a solvent-free ink is ‘dried’ to the substrate to which it is being applied via exposure to ultraviolet light. The technologies responsible for such production methods are still in their infancy in comparison to older, more developed techniques involving solvent based inks.

Ultraviolet, or UV, light is electromagnetic radiation with frequencies corresponding to a particular region on the electromagnetic spectrum. With frequencies typically ranging between 200 and 400 nano metres, UV radiation is outside the ranges of visible light. As a consequence of this, UV light cannot be seen with the human eye.

The UV-curable inks used in the printing industry  are referred to as ‘dry’ inks owing to the fact that they are not part of a solvent solution whereby the solvent evaporates (or ‘dries’) during the curing process. These inks are ‘cure-on-demand’; in short, they will only begin to cure in the presence of UV light of a sufficient intensity. This means that standard light won’t trigger the curing process, which has many benefits in manufacturing.

The presence of UV of a certain frequency and intensity activates a component in the ink called the ‘photoinitiator’, which begins the curing process. It should be noted that differing photoinitiators require varying frequencies and intensities of UV radiation to activate. Upon activation, the photoinitiator generates radicals which act as a catalyst in the process, curing the substances involved via the mechanism of polymerisation.

Since their advent, UV-cured inks have demonstrated some much sought after characteristics, which are constantly being further developed and enhanced. These advantageous characteristics include;

  • Being the aforementioned ‘cure-on-demand’ type inks.
  • Dramatically improved physical properties over other solvent based inks, such as; improved gloss, and improved scratch, abrasion and chemical resistance.
  • Faster production speeds, since these inks can cure very rapidly when designed to.
  • They contain no VOCs (volatile organic compounds) and as such are far more environmentally friendly.

These characteristics are already providing great advantages over previous printing materials and methods, and just like many other developing technologies, show an indication for even greater potential in the years to come.

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