LED technology has become a real alternative solution in the sphere of light curing. To date, the efficiency of both the individual LEDs and the system as a whole have been increased, resulting in further improved drying quality. Simple integration, dispensing with ozone and mercury and the lack of thermal radiation favour a broad range of applications for this technology in industrial curing.
Whether in the curing of printing inks, adhesives or varnishes on various substrates – LED UV curing is seeing high growth rates in coating industries. However, distribution of the two technologies differs widely in the various segments. Overall, LED systems are most frequently used in inkjet and adhesives applications.
In principle, the polymerization process with an LED system is identical to the familiar UV technology. The only difference is that the chemistry of reactivity and surface properties has to be optimized. If the aforementioned conditions are satisfied in terms of inks, varnishes, adhesives, coatings etc., LED systems are successfully used in a printing press, for example. This new curing technology is more and more used in inkjet applications.
For curing purposes, LED systems use the property of light-emitting diodes to convert electrical current straight into light. They are based on semiconductor compounds which give off energy in the form of ultraviolet radiation or even visible light as soon as electrical current flows through an LED in the forward direction.
Under what conditions does an LED system save electricity? This is probably the most common question in connection with LED technology and does not have just one simple answer; it always depends on operating and machine conditions.
It is now essentially possible to save energy when curing using LED systems, as the reactivity of the chemistry has been improved. In addition, an LED UV system is ready to use as soon as it is switched on, so there are no stand-by times. Format switching allows LEDs to be switched off outside the active working width. Triggered pause switching between individual products allows further savings. There is also energy-saving potential from having the right metrology options to determine intensity per unit surface area during the drying process.
The unit W/cm² has become established in metrology for LED systems. This unit is the value of maximum intensity per unit surface area. However, as intensity decreases as distance increases, the value immediately below the exit window is frequently quoted.
It should furthermore be noted that a suitable UV measuring system needs to be used. This is characterized by sensitivity which is high and as constant as possible in the wavelength range emitted by the LED. We would be delighted to provide you with information about this.
LEDs have already become a popular choice for lighting. LED UV technology has already made inroads in terms of curing printing inks in the printing industry, too. Applications in other industrial spheres are on the threshold, but awaiting the development of LEDs with shorter wavelengths.