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FLEXO Magazine : June 2014
Next generation polymers also retain the superior blade life offered by traditional plastic doctor blades. The physical properties of the material are engineered to make the blades last longer and wear more evenly. The blades are non abrasive with great chemical resistance and lubricity and they last up to four times longer than steel. SCORING, SAFETY, SPITTING Next generation polymer material will not separate, splinter or crack. Instead, it wears into nano particles without metal fragments that can pose a scoring risk. By comparison, steel doctor blades are the cause of many anilox roll scoring incidents. Improper blade installation and excessive blade pressure can cause small fragments of the metal blade to break away, become lodged against the roll and destroy rows of anilox cells as the roll turns. Once scored, the roll has to be resurfaced or replaced at a significant cost. While a printer can take steps to reduce anilox damage, the risk of doctor blade related scoring can be completely eliminated by switching to a next generation polymer blade. Using next generation polymer blades will also reduce the risk of cuts that can occur when operators are remov- ing the worn blades from the press. The advanced polymer material does not develop a dangerous cutting edge after use, so the worn blades are safe to handle compared to steel. As steel blades wear, their edges become honed through contact with the anilox roll, leaving razor sharp tips. As a result, steel doctor blades are responsible for a large number of pressroom injuries. In addition to the emotional impact of a workplace injury, there are substan- tial costs associated with accidents that occur on the job. These costs include: • An increase in insurance rates • More workman’s compensation claims • Medical bills • Labor replacement • Press downtime In addition to solving problems with blade life, pressroom injuries and anilox scoring, next generation polymer blades have been shown to resolve UV ink spitting. UV inks, often seen in high linescreen and specialty process work, are being used more frequently to speed up turnaround times and increase throughput. UV inks are difficult to meter, however, and ink spitting is a problem that plagues many flexographic printers. UV ink has a normal viscosity of five to seven times that of water and solvent based inks and its thixotropic properties—the ability to thin out when agitated—make it transfer differently on press. The thicker ink consistency puts excessive pressure on the metering blade, often resulting in hydroplaning, or “spitting,” and contamination of the printed image. Due to their lubricity, rigidity and lower surface energy, advanced polymers have a significantly lower dyne level than steel. This decreas- es the attraction between the next generation polymer doctor blade and UV inks and facilitates a more fluid transfer of ink to the plate. SPECIALTY INKS & COATINGS As packaging printers turn to specialty coatings and tactile finishes, such as glitter, pearlescent and soft touch to make products more appealing, they are forced to deal with shorter blade life. The abrasive characteristics of these new formulas can accelerate wear on steel doctor blades. The next generation polymers are extremely abrasion resistant and are chemically compati- ble with all specialty inks and coatings. By switching to these new polymer materials, printers can get better prod- uct quality and longer life out of their doctor blades. Today’s innovations in polymer doctor blades provide printers with a versatile product that can deliver the best of both steel and plastic. A combination of advanced materials and MicroTip technology has produced a blade that meters as well as steel in the most demanding graphics applications while retaining the safety and long life benefits of traditional plastic. As a bonus, these new materials offer a solution to UV ink spitting and compatibility with today’s innovations in ink and coating technology. n About the Author: Kevin McLaughlin is the president of Flexo Concepts, which manufactures TruPoint nonmetallic doctor blades and MicroClean anilox cleaning equipment. He has more than 24 years experience in the industry and has obtained a broad knowledge of the many aspects of flexo printing. Kevin acquired Flexo Concepts in 2001 and has been successful in securing the company’s position as a leading global supplier of nonmetallic doctor blades. Flexo Concepts is located in Plymouth, MA. “Today’s innovations in polymer doctor blades provide printers with a versatile product that can deliver the best of both steel and plastic. ” 82 FLEXO | JUNE 2014