by clicking the arrows at the side of the page, or by using the toolbar.
by clicking anywhere on the page.
by dragging the page around when zoomed in.
by clicking anywhere on the page when zoomed in.
web sites or send emails by clicking on hyperlinks.
Email this page to a friend
Search this issue
Index - jump to page or section
Archive - view past issues
FLEXO Magazine : January 2012
Technologies & Techniques Quicker, Simpler Plate Mounting improves the entire Printing Process By Joe Prunier Changes in flexographic printing are happening faster than ever. Press speeds are up and new plate and sleeves technologies facilitate vastly improved print quality. The market is demanding increasingly shorter printruns to reduce working capital and allow for faster in- novations in packaging graphics and promotions. The key to being successful in this business environment is produc- tion efficiency. To thrive, it is essential that all processes be optimized to expedite job changes and reduce downtime wherever possible. STATE OF INDUSTRY Currently, the average length of a flexographic print job is around 50,000 meters, often less. It is not uncommon for printers to print six to eight, or even 10 jobs per day. The faster the printer can execute job changes, the more print jobs it can process. The more jobs it can process, the more appealing the printer appears as a supplier. To compete in this environment, print quality is an absolute must. To profit in this environment, the printer must have a highly efficient and repeatable process. ADHESIVE BONDS One area of process enhancement lies within printing plate mounting and demounting practices. The key to an ef- ficient and repeatable process for mounting and demounting flexographic printing plates lies in the adhesives which are used on mounting tapes that bond print cylinders and sleeves onto printing plates. The requirements are simple: Bond to the sleeves/cylinders and plates as securely as possible during printing to completely eliminate any possibility of plate edge lifting or bubbling, and when the job is done, remove as easily as a siliconized liner. To overcome edge lifting, printers have used primers, magic markers, edge sealers and tapes. Additionally, many printers have used adhesion blockers (such as talc, chalk, soap or shellac) to make removal easy, so as not to destroy the plates. All of these techniques, however, make it extremely difficult to create a standard operating procedure that is ef- ficient and repeatable. To achieve repeatability and efficiency, the printer must choose a proper plate mounting tape spe- cifically engineered with today ’s printing technologies and processes in mind. KEY INGREDIENT High printing quality is directly associated with quality foam used in plate mounting tapes as a plate cushioning or support medium. Manufacturers can use the most technologically ad- vanced foam formulations to promote the highest print quality from today ’s plate technology. Most all plate mounting tapes have what is called a differ- ential adhesive; there are two completely different adhesives on either side of the tape. • The “open-side” or the side that is not covered by the siliconized liner, is designed to bond to the sleeve or cylinder. It can have adhesives that are specifically for- mulated to bond to and release cleanly from either steel or polyurethane (the two most commonly used materials for cylinders or sleeves). Other materials used for sleeves such as Mylar, nickel Kevlar, etc have similar characteris- tics and will bond in much the same fashion. • The “plate-side,” or the side that is covered by the silicon- ized liner, is designed to bond to flexographic plates in preparation for printing, and remove from those same plates without tearing, stretching, or leaving residue. 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 and short repeat lengths will have high bonding strength to keep the plate edges down during print- ing. Because these plates are thicker, they will be more resis- tant 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 plates edges from lifting during the printrun, but will allow the plate to release cleaner and easier after the job is finished without tearing or stretching. TECHNOLOGY TO WATCH Differential Adhesive Mounting Tapes • Introduction Date: 2011 • Benefits: Eliminates plate lifting and bubbling • Impact: Efficient, repeatable standard operating procedures • Experience: High print quality, fast and precise recov- ery after compression, high print speeds, long runs • Watch for: Optimized, expedited job changes, re- duced downtime • 2012 Exhibitions: INFO*FLEX, Labelexpo Americas 38 FLeXO January 2012 www.flexography.org