Ink mileage curves have been studied for many years. Several models for curve fitting have been reported by different researchers. The regression coefficients derived from curve fitting were found to be very useful for comparing different inks and were related to some properties of ink and paper. However, these models were based on the experimental data of prints made on IGT and/or Prufbau printability tester using offset inks. The quantity of transferred ink, and hence the amount of ink on paper, was determined by the weight difference of theprinting disc before and after printing. Therefore, these models cannot be applied to the ink mileage behavior of other ink types, nor on commercial printing presses.
Recently, water-based inks have been of more and more interest to the printing and ink industry because of their environmental benefits. Compared with solvent-based inks, water-based inks have more complex formulations because of their higher surface tensions, lower drying speed, foaming problems, pH balance, and different rheological properties. The transition from solvent-based to waterborne inks has been facilitated by advances in both the chemistry and the printing technologies employed. With the new development in rheology modifiers and their increasing application in water-based gravure inks, a more complete investigation of their chemistry, thickening mechanism and effects on water-based gravure ink systems is necessary. This paper explores the significant effects of various rheology modifiers, including non-associative and associative thickeners, on the rheological properties of a water-based rotogravure ink system. Particular emphasis is given to thickening efficiency (viscosity profiles of each rheology modifier in a model system), pH stability, particle size, system compatibility, temperature stability, and printability on vinyl substrates. Wire-wound lab rods and a Moser Sheet-fed Gravure Proofing Machine were employed to produce printed samples for characterizing the performance of the formulated inks. The purpose of these investigations is to acquire a complete understanding of rheology modifiers’ effects on the water-based ink system, as well as to help select appropriate rheology modifiers for water-based ink systems in order to achieve better print quality.
Dr. Margaret Joyce, professor of paper engineering at Western Michigan University (WMU) in Kalamazoo, Wis., is among those at the forefront of intelligent printing. In September, Joyce was awarded a grant of close to $1 million to study printed radio frequency identification (RFID) tags with an eye on their use for homeland security. In her research, Joyce will evaluate the effectiveness of both flexographic and gravure printing methods for this application and will seek to better understand and identify the various ink, substrate, and press materials needed to optimize performance of printed RFID tag technology.
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