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FLEXO Magazine : February 2013
the sleeve or cylinder. It can have adhesives that are specifically formulated to bond to and release cleanly from either steel or polyurethane (the two most com- monly used materials for cylinders of sleeves). Other materials used for sleeves, such as mylar, nickel, kevlar, etc., have similar characteristics and will bond in much the same fashion • The “plate-side” adhesive, or the side of the tape covered by the siliconized liner, is designed to bond to flexo- graphic plates. It has a very unique adhesive system that bonds to flexographic plates and then releases from those plates without leaving residue or without tearing or stretching. It is extremely important to bear in mind that there are many different kinds of plate-side adhesives designed to work with different plate thicknesses. An adhesive that is designed for a .107-in. plate will have high bonding strength to keep the plate edges down during printing. Because these plates are thicker, they will be more resistant to stretching or tearing An adhesive that is designed for thinner plates (.067- in. or .045-in.) will have a lower adhesion level that is sufficient to keep plate edges from lifting during the printrun, but will allow the plate to release more cleanly and easily after the job is completed, without tearing or stretching • Using a tape with an open-side adhesive that does not match the sleeve or cylinder will result in increased bub- bling between the tape and sleeve/cylinder, or perhaps cause difficult demounting that will require labor-inten- sive cleaning to remove adhesive and foam residue. • Using a tape with a plate-side adhesive that does not match the plates with which you are printing will result in edge lifting or destroyed plates. For all of the above reasons, it is critical to consider the sleeves/cylinders and plates you are printing with and match them with a compatible adhesive system to optimize your printing process. Failure to do so can result in wasting thou- sands of dollars and hours of valuable production time. Foam Factor High print quality is directly associated with the quality of the foam used in plate mounting tapes which serve as plate cushioning or support mediums. The quality of the foam and how the foam is integrated into the adhesive tape is critical in determining print results. Manufacturers can use the most technologically advanced foam formulations to promote the highest print quality for today ’s plate technology. If, however, the wrong foam/adhe- sive combination is used to adhere the tape to the sleeves/ cylinders and the plates to the tape, the result can include destroyed plates and labor-intensive cleaning on sleeves and cylinders with toxic chemicals. Ideally, printers should take the time to determine which open- and closed-side adhesives are most compatible with their plates and sleeves/cylinders. Once the optimal adhesive combination has been specified, printers can then focus on which foam hardness produces the best print results. Today, plate mounting tape manufacturers are producing five or more different foam hardness levels in order to allow the artwork the best solid ink density coverage, least dot gain in process and highlights, and the best balance with combina- tion plates. Once this delicate balance between artwork, foam hardness, and adhesive combinations has been established, printers will be able to fully maximize their print processes by reproducing the best print quality at the highest speeds with the least amount of downtime and transition time between jobs. taPES, taPES & morE taPES In addition to the all-important plate mounting tapes, a vari- ety of additional adhesive tapes can play a very important role in optimizing production processes. Let’s take a closer look: Splicing Tapes – these tapes are critical for splicing web-to-web materials together, particularly in live production environments. Roller Wrapping Tapes – wrapping select press roller cylinders with this unique tape can help to ensure that the printed substrate maintains its integrity as it moves through- out the production process. Edge Sealing Tapes – these tapes can be used to rein- force the bond between the photopolymer plate and the print cylinder. Core Starting and End Tabbing Tapes – tapes are often used to adhere a new web to its starting core; they are also used to secure the top layer of a finish roll. By understanding the interrelationship between the materi- als used in the printing process, including the all-important adhesive tapes, today ’s flexographic printers can achieve optimized production efficiencies that increase throughput and impact the bottom line. n About the Author: Joe Prunier is market manager, print & web processing, tesa tape, inc., Charlotte, NC. www.flexography.org february 2013 FLEXO 59