How is UV LED technology connected to the printing industry?

Being asked about printing technology, most of all people will refer to home printers or copy/orienting shops. But these printer types are only a fraction of what actual printing technologies are and which applications are covered. From newspapers, to wallpaper, to packaging to bottle labels, all of these are printed materials and require specific printing processes.

What do all these methods do have in common? Drying with ultraviolet (UV) light, in short UV drying. This method enables drying the ink while still printing. Just be aware that UV is not widely used for home printing, where still heat is the chosen method to dry inks. Instead, commercial and industrial printing are the main areas where UV drying is implemented.There are several options of how to integrate UV light into the printing process. Due to the development of the last years the technology fastest growing is light emitting diodes, short LED. Depending on the printing process, UV LEDs can be placed either at the end of the process after the ink is placed on the surface or it is placed in intermediate positions if the printing process is carried out in several steps. Different than in traditional UV light bulbs, UV LED luminescence is generated when electrons move through a semiconductor (diode) which emits energy in form of protons. The light emission and with that the specific wavelength relies on the type of materials in the semiconductor.Curing of inks with ultraviolet light is a complex chemical process. It is based on crosslinking and therefore hardening an ink by creating new bonds within oligomers with the help of a photoinitiator. A photoinitiator is a substance that reacts to specific wavelengths and produces a chemical reaction where some bonds are broken, and some others formed. These new bonds then form a rigid three dimensional network.
Schematic drawing of the interaction of UV LED light with a photoinitiator
Figure 1 - Schematic drawing of the interaction of UV LED light with a photoinitiator

Ink curing as described in picture 1 offers certain advantages compared to other methods used by some other such as hot-air drying. LED curing technology significantly reduces the surface temperature. Less heat means less energy wasted, which also means less costs for the application itself. On top the low power consumption of LEDs is one of the main advantages as they offer up to 70% of electricity-cost saving compared to hot air drying. A further benefit of implementing LED into printing technology is that LED offers fast on/off option allowing them to only be used when required, which again helps saving on energy costs.

The UV LED market in the printing industry is a fast growing one as there are more advantages such as its versatility and adaptability to various printing machines. Heraeus Noblelight offers water and air cooled systems in various power ranges even including systems for easy maintenance (Plug-and-play) – click  here to learn more.



References:
Kipphan, Helmut. (2001). Handbook of print media: technologies and production methods. Berlin: Springer

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