News from NAPP

By: Jim Rosenberg Each side of the Newspaper Division of MacDermid Printing Solutions faces some sticky problems.

Besides summer start-up of its plate plant in Wigan, England, MacDermid has intensified its focus on flexo, according to Research Director Dave Roberts, with more investment in research and development, including staff and continued examination of water-wash improvements.

The top research topic has been sticky plates, he told production personnel and their various vendors in June at the annual Newspaper and Publication Flexo User Group. (See "What's Next for Flexo?" in the October print issue of E&P.)

NAPPflex HS II plate users found that because paper starts through a press before ink is applied, the plate's sticky surface sometimes pulls at the sheet. NAPP Systems looked into the resin, roll coating, and an additive in the FP cleaner.

Though the coating and additive helped, Roberts said, they did not address the problem's cause. One of 70 new resin fomulations studied was eventually chosen, and "we did find that we could reduce the resin stickiness by about 75%," he said.

Following satisfactory alpha testing on "a handful of plates," he continued, almost 3,000 with the reformulated resin were shipped for beta tests at The Daily Gazette in Schenectady, N.Y., and the Reading (Pa.) Eagle, where results are expected shortly. And 2,000 of the 8,000 to be run at La Repubblica's plants in Italy tested well, according to Roberts. With stickiness eliminated, he says, testing now aims now to ensure runnability.

From the division's Polyfibron products side, opportunities for improving plate cushions include easier removal, longer service life, and improving print quality "by better matching the physical characteristics of the cushion to the plate," said Roberts.

MacDermid is working toward a low tack to reduce smutting--blemishes caused when ink and paper contact a plate's non-image area--and has been field-testing adhesives. The trick is creating a cushion with just the right smoothness against the plate and just enough--but not too much--grip on the cylinder.

In a third area, MacDermid has been working with PerkinElmer on LED bump technology--already used in PerkinElmer's laser platesetter--that soon will be part of NAPP's conventional platemaking system. Consisting of hundreds of light-emitting diodes, the bump exposure for preparing plates for imaging also can be retrofitted to NAPP's installed exposure units.

The retrofit will differ from the platesetter's unit in two respects: For affordability, it will not be the unit PerkinElmer custom made for its imager; nor can it be stationary over a moving plate, but instead must scan a stationary plate.

According to Roberts, the LED bump should provide more uniformity of exposure on less power and at a lower temperature, with instant-on capability and long service life. Uniformity, said Roberts, should translate to better, more consistent quality. To achieve it, MacDermid is testing a prototype, trying to "smooth out hot spots and cool spots across the LED array," he said.