UV LED Technology in Flexo Platemaking
|Eskso XPS Cyrstal in our Atlanta Innovation Center|
UV LED Advantages
At this point, we need to take a step back into the “so what” question – why are we even interested in UV LED curing to begin with? The answers relative to flexographic platemaking are short and simple:
For productivity purposes, we merely point to the expanding trends of “inherently flat top” formulations that have integrated into the market within the past few years, which was pioneered by, ahem…MacDermid. These formulations have changed the way we view formulation possibilities, and have increased the platemaking speed and efficiency as a result. Therefore, our “new normal” has changed - speed is here, and UV LED can help to enhance the control of these types of formulations during platemaking even further.
Now that the stage has been set for the importance of UV LED technology and its growing impact, how do we as formulators deal with this technology? The ink formulators have borne the brunt of this emergence thus far - being forced to contend with reformulation efforts, new raw materials, functional differences, etc. On the platemaking side, there are essentially two possibilities we are forced to face: how do our current formulations interact with UV LED curing systems, and how do we modify or develop new formulations that take advantage of these light sources? Let’s discuss…
While the existing UV LED platemaking systems do target the same peak wavelength for curing (365 nm) UV LEDs are inherently near-monochromatic (See Figure 1), i.e. a very narrow wavelength distribution, when compared to fluorescent bulbs (See Figure 2).
|Figure 1: Spectral Output of LED Exposure Unit|
|Figure 2: Spectral Output of Fluorescent Exposure Unit|
As a result, photopolymer formulations that were developed with broad band bulbs in mind can quite possibly behave differently, and unpredictably with these new systems despite their wavelength target similarities. To date, there are many formulations that have become “qualified” in these systems, so it’s safe to say we, as the plate developers, have had a bit of serendipity with respect to the interactions between plates and light sources. There are, however, things that we have learned about along the way that will help guide us on where to go next.
1) Productivity…back again!
MacDermid Graphics Solutions' (MGS) Technology Strategy
- The outstanding uniformity of consistency of photopolymer plates derived from UV LED platemaking, and the print benefits obtained therefrom.
- The ability to automate platemaking.
- The increasing environmental pressures that will ultimately impact mercury-based light sources that are found in the existing bank light systems on the market today.
Productivity and sustainability…last time - we promise!
- High quality formulations that exist TODAY, qualified and proven to work in UV LED systems. These include resins such as Digital RAVE and LUX ITP 60.
- Newer technology platforms that are developed to be “tuned” to UV LED light sources, providing even greater productivity and wider performance latitude than plate technologies that currently exist.
Based on article, “UV LED & Photopolymer Technology” by:
Ryan Vest, Global Director of Innovation - MacDermid Graphics Solutions