Barrier printing of bags for food waste

摘要

The grease resistance of paper bags for domestic food waste was improved by a printed barrier. Barrier layers wereprinted in a full scale flexographic printing press using one, two or three printing nips. Two different substrates wereused. The barrier printed sack papers were then converted into sacks and oil and grease resistance of the sacks wastested in a controlled laboratory environment.The coverage of the substrate depended on the number of nips and the permeability of the substrate. The morepermeable substrate showed a high amount of coating penetration and consequently a poor coverage of the barriercoating while conventional sack paper showed a lower penetration of the barrier coating and a better coverage of thesubstrate.The barrier printed paper bags showed generally good resistance to water while tests of oil and grease resistance ofsacks revealed that the printed barrier layer would not give a complete grease resistance. A barrier layer would onlypostpone the oil and grease penetration. Grease penetration would generally start at the folds. SEM cross sections offolds revealed that a thicker barrier and a better coverage of the barrier layer would lead to a lower exposure of fibresinside the folds.