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FLEXO Magazine : April 2010
and FIRST says, Flexographic press dryers utilize hot air to remove the volatile portion of the ink from the printed substrate. As the hot air contacts the printed substrate, the temperature of the substrate, ink solids, and ink solvents increases, resulting in evaporation of the ink solvents. There are two types of flexographic press dryers: • Between Color/Interstation Dryers: These remove a sufficient amount of the volatile solvents from the printed substrate to allow for a dry trap of the next down color. • Main Tunnel/Overhead Dryer: The overhead dryer removes the volatile solvent from the last print station and completes the heat setting of all the inks applied to the substrate. TEST says, All too often press operators lose sight of the fact that it is a specific combination of both heat and air that dry the ink. Dryer manufacturers stress what they call the three Ts of drying: Time, Tempera- ture, Turbulence. The effectiveness of an oven can be measured by the time available for drying. This of course translates into the oven length on a web-fed press. The correct use of temperature is es- sential to accelerate the evaporation of the solvents from the ink. And finally, efficient air turbulence can overcome the negative influence of the boundary layer. For more information, see Section 22.1 (Page 247) Drying Solvent & Water Based Inks & Coatings What is FIRST The intention of FIRST is to provide all participants in the flexographic reproduction process with a common set of guidelines, tutorials and data that can be used as communication and production tools. The aim of FIRST is to create a common set of specifications and commu- nication protocols for the industry. This platform should establish common communication and identify the responsibility of the provider(s). To order FIRST, call 631-737-6020 or visit www.ftastore.com . What is TEST TEST is the educational arm of the Flexographic Technical Association. The aim of TEST is to align all of the training materials available through the FTA with the guidelines, tutorials and data identified in FIRST. TEST is focused on implementing new learning methodologies to reach out to a larger portion of the FTA membership. For more information on TEST, visit www.flexography.org. FLXApril10_v1.indd 49 4/9/10 4:31 PM
Sustainable Winter 2010