LED-UV requires 25% of energy consumption as compared to UV lamps

Ramu Ramanathan (RR): First and foremost. Is UV cool or not? 
Prashant Atre (PA): It is cool to print with UV, but with LED-UV, it is cooler. 

RR: Please explain.
PA: This is because less heat is generated in the process, as compared to conventional UV lamps. This makes LED-UV a promising curing technology for heat sensitive substrates like thin films and flexibles. Every technology brings some advantages and some challenges. LED is cool, but works on a single wave-length as compared to UV which works on a band of wavelengths. This makes limited choices for raw materials for LED ink and coating formulations.

RR: In the past 10-15 years, printing’s major advances has been the development of cool running, low-power consumption and UV-LED lamps that use a fraction of the power of heat driers. True or false? 
PA: The difference between UV and LED-UV is very similar to that of a continuous tone photograph and a half-tone printed picture. As the half-tone printing has improved over the years, so has the LED-UV technology with more diodes per square-cm. This makes LED-UV better and faster for curing of inks and coatings.

RR: Better and faster in what way?
PA: It takes two to cure, chemistry and curing energy (UV, LED, EB or heat). If the energy is strong, the chemistry can be weak. But, if the curing energy is weak, then we need chemistry to be strong, thus impacting the pricing of inks and coatings. While LED-UV has made inroads in commercial printing and labels through flexo process, it has to make an impact in carton packaging and flexible packaging segment.

RR: While ultraviolet curing used to be an expensive process with hazardous chemicals and high-pressure metal halide lamps that ran very hot (and emitted toxic ozone), UV-LEDs have changed the game. How so?
PA: It would be wrong to say that conventional UV inks are an expensive process with hazardous chemicals. The chemistry is common for both UV and LED-UV and hence, based on what an ink manufacturer chooses, it can be hazardous or a very safe UV chemistry. LED-UV is surely a future in all segments of life and the printing industry is no different to it. It is a matter of time, the efforts by formulators of inks and varnishes, and government regulation to ban mercury use (conventional UV lamp) which will determine the speed of transition from UV to LED-UV or to EB.

RR: TUV-LED arrays can be fitted easily into flexo presses for labels and packaging, which have used UV curing for years. 
PA: The world of print is seeing an increasing trend of LED-UV in the label printing market for narrow web flexo process, allowing label printers to choose thinner films, thus saving material cost. However, as I said earlier, this ink reality is not the norm among the Indian carton packaging segment. The LED-process UV will see real success when this transition happens from UV to LED-UV for the carton packaging segment as well.

RR: The most significant change in the past 10 years has been in litho presses, which can now take advantage of modern lamp arrays’ compactness and affordability, and fit them into existing press designs. Which are the preferred lamps?
PA: The biggest advantage with LED-UV is savings through energy cost and lamp life. Apparently this makes the most attractive proposition, But, without the active support of LED-UV inks and varnishes in terms of press performance and pricing, this will remain a theoretical discussion. Here, it is important to ask a question as to why new offset machines for the carton packaging segment are still getting installed with conventional mercury UV lamps and not with LED-UV.

RR: What are the Arets (Toyo) solutions available in India?
PA: Toyo Ink Europe in Belgium (the mother plant of Toyo Ink Arets, India) is focused on food packaging, LED-UV inks and varnishes for narrow web flexo and offset applications. Also, we have standard LED-UV for non-food applications. The LED-UV for flexo is rapidly growing.

RR: Finally, any message for brand owners and packaging designers?
PA: Brand owners are increasingly emphasising to packaging converters about reduction in carbon footprints and more sustainable solutions. I feel LED-UV and EB can be a major step in this direction. 

RR: EB inks can be another Tech-Talk. Thank you.