Sun Chemical has begun production of its flexographic UniQure inks, colors that can be applied in multiple layers to paper or film without curing between print stations. The inks are cured using either electron beam (EB) or UV light only after the final layer of ink or varnish is applied. At present, the process, which is called WetFlex EC, must take place on a central impression press.
Officials of Sun Chemical, Ko-Pack International and Energy Sciences Inc. (ESI) demonstrated the process recently at the ink company’s technology center in Carlstadt, NJ. Ko-Pack manufactured the press used for the demonstration, and ESI manufactured the EB unit used for the cure.
The UniQure inks are applied to the substrate using standard photopolymer plates. Because there are no turning bars on the CI press, the printed inks do not risk smearing by contact with press parts. Once printed, the ink is nearly dry to the touch, thereby eliminating the risk of color migration to other plates in the rotation. Printing at high speeds is possible, and the inks produce no VOCs.
With the EB cure, no odors are produced, and the inks are safe for contact with anything, including food. EB curing units have traditionally been very large and very expensive, and therefore not encountered in narrow web print shops, but the size and cost is dropping, says Edward Maguire, ESI’s vice president of marketing and sales. The company’s smallest unit is 20" wide, and sells for about $250,000. With UniQure inks and one EB unit, no curing is needed at each station.
The requirements of the WetFlex process include an enclosed doctor blade system, an appropriate pumping