RadTech UV+EB 2016 exceeded expectations for many. Attendance was at an all-time high with more than 1,400 attendees, including many new to RadTech. The UV-curable market is growing and attracting new people to the conference. Much of this growth is being fueled by interest in UV LEDs, which have opened new applications for UV-curable inks and coatings.

Technical Program Highlights Growth of UV LED Adoption

For many, the technical program is the highlight of RadTech UV+EB. This year’s conference did not disappoint; the technical program was stacked with informative presentations on topics ranging from photoinitiators for UV LED curing to oligomers for 3D printing. More than 25 presentations focused on UV LED technology.

The push to adopt UV LEDs is strong, and researchers are focused on developing solutions that will facilitate their adoption. One of the main barriers to widespread UV LED adoption is their incompatibility with existing photoinitiators. However, formulators are responding to the market’s demand and are developing new photoinitiators that are compatible with UV LEDs.

Development of UV LED-Compatible Photoinitiators

IGM Resins won the best technical paper award at RadTech UV+EB 2016 for their development of a new photoinitiator for UV LEDs. In the presentation “Design of New 3-Ketocoumarins for UV LED Curing,” Dr. Marika Morone shared her team’s research to develop a photoinitiator for 365 nm and 395 nm wavelength UV LEDs. Their research produced a photoinitiator that has low oxygen sensitivity while also maintaining high reactivity and solubility. It also resists yellowing, which has been a critical issue for many looking to adopt UV LEDs. The photoinitiator is suitable for pigmented systems, such as inkjet, offset, flexography and screen.

In the presentation “Innovations in Photoinitiator Technology for LED Applications,” Mike Wyrostek, Hampford Research, shared research on norrish type-1 and type-2 photoinitiators. They found that they could modify the quality of the cure by tuning the ratio of photoinitiators.

Much of the photoinitiator research shared at RadTech was focused on UV LED-compatible photoinitiators. Other presentations included:

  • UV-Curable Formulations for Deep-UV LEDs, Haruyuki Okamura, Osaka Prefecture University;
  • Dendritic Oligomers for LED-Curable Formulations, James Aerykssen, Dymax Oligomers & Coatings;
  • Highly Reactive Thin Film Hardcoats for Plastics, Marcus Hutchins, Allnex;
  • Formulating a UV-Cure Pressure Sensitive Adhesive for PVC Foam Tapes and Converting an Oven-dry Waterborne Material Using an LED Lamp Cure System, Brooke Shell, Novagard Solutions.

Mixing UV LED Wavelengths

Others have responded to the challenge with a different approach. Some light system manufacturers, such as Digital Light Lab, are developing arrays that contain more than one wavelength, which could ensure compatibility with existing photoinitiators and help to reduce the burden on chemical manufacturers to reformulate for UV LEDs.

Kopp Glass’ UV glass mixing optic takes a similar approach in that it doesn’t require photoinitiator reformulation. We presented this new research at RadTech. In his presentation, Brian Jasenak demonstrated how our new UV glass optic can mix light from UV LEDs with different wavelengths and produce a single irradiance pattern with uniform intensities of each wavelength. Innovations such as these are helping to advance UV LEDs so that end users can realize the benefits of better efficiency and lower operating costs, long life and greater substrate choices.

Exhibitors Featured New UV LED Products

A new addition to the technical program was a track dedicated to new product debuts. Manufacturers were invited to present 15-minute product demonstrations; 20 companies participated in the track. The product demonstrations were well received, and in many instances, the conference hall was packed with standing room only.

GEW’s product demo featured their ArcLED Hybrid UV-curing system, which allows printers to use both UV LEDs and conventional arc lamps on the same press and reap the benefits that both provide. They also highlighted their multipoint UV monitoring software that gives the user better process control.

At both their booth and during their product demo, Nichia promoted two UV LED products; the UV LED NVSU233A produces peak wavelength emissions of 365 nm to 405 nm. It can reach an efficacy of 1,400 mW when driven under 1,000 mA. Also discussed at their product demo was the UV LED NVSU119C, which emits at 375 nm to 405 nm. When driven at 1,000 mA it can reach 1,340 mW. Both of these products are suitable for UV LED ink printers.

Sensor Electronic Technology, Inc. (SETi) was also present at the conference with their new Violeds products on display. SETi was recently acquired by Seoul Viosys; before this, they had been working together for more than a decade to commercialize UV LEDs. Their products span the UV region, with UV LEDs available from 225 nm to 405 nm. They recently launched new UVC LEDs that emit at 275 nm and can reach 30 mW when driven at a current of 350 mA and 10 mW at 100 mA.

Overcoming the UV LED Learning Curve

Despite the excitement surrounding UV LEDs, there are still some concerns about the technology, and many are exploring adoption cautiously. For many, UV LEDs present a steep learning curve. During presentations, questions were asked about UV LEDs and their readiness for the UV-curing market. In particular, there seems to be a gap in understanding if UVC LEDs are commercially viable. To remedy this information gap, RadTech included in the technical program a four-hour short course on UVC LEDs titled, “All You Ever Wanted to Know (and more) About UVC LEDs and Applications.”

Throughout the short course, examples were given that demonstrated that UVC LEDs are commercially viable and are being used for applications. While UVC LED manufacturers are striving to improve performance, the technology is already efficient enough for some applications today. To help overcome the learning curve, it’s important to collaborate closely with your suppliers to understand how they can help you design an LED system that will meet your performance goals.

Additional Reading on UV LEDs

Because UV LEDs are new to many within the UV-curing market, our company has collected several resources that could be helpful to those considering adopting them. You can find these resources in the list of references below. As you reflect on the new ideas and research shared at RadTech UV+EB 2016, we hope this information helps you harness the benefits that UV LEDs offer. 

1. Heathcote, J. UV LED Overview Part 1 – Operation and Measurement. RadTech Report, July/Aug. 2010, p. 23-33.
2. Heathcote, J. UV LED Overview Part 2 – Curing Systems. RadTech Report, Sept./Oct. 2010, p. 31-42.
3. Heathcote, J. UV LED Overview Part 3 – Diode Evolution and Manufacturing. RadTech Report, Spring 2011, p. 43-50.
4. Hechfellner, R.; Landau. S. Understanding LED Performance. Philips White Paper, http://www.lumileds.com/uploads/14/NA05-pdf.
5. Jasenak, B. How to Design with LEDs: Iterative Approach Yields Fully Optimized Lighting Systems, Kopp Glass website, http://www.koppglass.com/blog/how-to-design-with-leds-iterative-approach-yields-fully-optimized-lighting-systems/.
6. Product Reference Sheet, Designing a UV LED Light? Not Sure Which LED to Choose? Kopp Glass, http://go.koppglass.com/available-uv-leds-2016
For more information, visit www.koppglass.com.