A very demanding application of double side coated foam tapes is the mounting tape for flexographic printing clichés. During the printing process a compressible medium, the foam, has to provide the printing pressure which enables the transfer of the ink to the substrate. The printing pressure should remain on a constant level throughout the complete printing job, which can last hundreds of thousand cycles. Tight thickness tolerances, high inner strength and a precise compression stress-strain deformation behaviour of the foam are additional factors which contribute to the complexity of this application.
In this presentation we will introduce various test methods used to evaluate the performance of foam in this application. The results of a number of foams, including representatives of both groups of crosslinked polyethylene foam and polyurethane foam, are then compared in terms of their suitability as compressible medium in long-lasting flexographic printing tapes.