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FLEXO Magazine : June2010
Technologies & Techniques 34 FLeXO june 2010 www.flexography.org and well cured after EB exposure with nitrogen inerting. When wet ink samples are EB irradiated in air, oxygen diffuses into the ink layer and effectively inhibits the curing. When inks are partially UV cured the solid or “gelled” ink limits the diffusion of oxygen and allows EB curing without interting. This interest- ing synergistic effect of dual UV-EB was not previously noted in earlier references on dual UV-EB ink curing.2 - 5 The cost of nitrogen inerting can be significant for com- mercial installations. This capital and operational cost of UV lamps in dual UV-EB curing installations may be partially offset by eliminating the need for nitrogen. ConClusions EB curing was very effective for completing the cure of par- tially UV cured flexographic inks. An additional benefit of the dual UV-EB curing is the elimination of the need to inert the EB curing process. These systems appear to offer good potential for commercial package printing installations. Table 4. ink Properties after Combined uV and eB Cure Tape Adhesion (%) MEK Resistance UV 75 mj/cm2 EB 30 kGy UV 100 mj/cm2 EB 30 kGy 150 mj/cm2 EB 30 kGy UV 75 mj/cm2 EB 30 kGy 100 mj/cm2 EB 30 kGy 150 mj/cm2 EB 30 kGy Cyan 2.65 OD 30 20 40 2 2 3 Cyan 2.73 OD 60 50 40 2 2 4 Magenta 2.61 OD 60 40 90 4 4 3 Magenta 2.69 OD 70 80 60 4 4 4 Yellow 1.39 OD 10 20 20 2 3 4 Yellow 1.44 OD 20 30 20 2 2 4 Black 1.95 OD 100 100 100 3 4 4 Black 2.07 OD 100 100 100 4 5 5 FuTure Work Additional work planned includes the demonstration of dual UV-EB curing on a commercial printing press. The pho- toinitiator package will be optimized to provide just enough UV curing for dry trapping ink prior to final EB cure. Migration testing is planed to confirm that the printed substrates are suitable for food packaging applications. n reFerenCes 1 M. Laksin, V. Linzer, T. Best, J. Modi, S . Chatterjee, TAPPI PLACE Division Conference, August 2004. 2M. Wismer, G. Gerek, US Patent 4,070,497, July 24, 1978 3J. Lovin, L. Keller, US Patent 5,407,708, April 18, 1995 4M. Laksin, W. Wilczak, US Patent Application 2007/0289459, December 20, 2007 5M. laksin, S . Chatterjee, RadTech 2008 Conference Proceed- ings, Chicago, May 2008. 6Nestle Corporation, 2009 Figure 4. Magenta ink samples uV cured at 150 mj/cm2 at two differ- ent application weights (700lpi, 2 .27bcm2 application on left, 900lpi, 1.36bcm2 application on right). Adhesion and MeK resistance shown before and after subsequent eB cure. Figure 3. Magenta ink samples uV cured at 75, 100, and 150 mj/cm2. Tape adhesion and MeK resistance is shown before and after subse- quent eB exposure. Figure 5. Magenta ink uV cured at 100 mj/cm2. Tape adhesion and MeK resistance shown before and after subsequent eB exposure in air and in a nitrogen atmosphere. Toll-Free: 866.282.7697 • Toll-Free Fax: 800.223.6869 • info@AndVre.com www.AndersonVreeland.com theDif f e rence! Experience Expanding the bubble-free flexoscape to meet even more customer expectations AUTHORIZED DISTRIBUTOR From mostly solids to maximized dot process work, you can find exactly what you need in the ever widening line of 3MTM Cushion-MountTM Plus Flexographic Plate Mounting Tapes. Best of all, these tapes are brought to you by Anderson & Vreeland, with almost 50 years of flexo platemaking experience. 18 Series firm tapes for mostly solids in a combination of solids and halftone images. 17 Series medium firm tapes for slightly more solids in a com- bination of solids and halftone images. 15 Series medium tapes for high speed printing with fine type reverses & expanded color gamut. 10 Series standard combination tapes when solid and halftone areas are equally important. 13 Series medium soft tapes for high speed printing of combination work when halftone areas exceed solids. 19 Series soft tapes to improve tone reproduction when process and halftone images predominate. 11 Series process printing tapes with low density to maximize dot reproduction for high quality process and screen printing. Across the line Easy Mount Adhesive for virtually bubble-free mounting. Combination Printing Process >>> >>> New! AV 3M ad 9404.indd 1 5/6/10 9:26:24 AM FLX_June2010_mech.indd 34 6/10/10 9:39 AM