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FLEXO Magazine : February 2014
TECHNOLOGIES & TECHNIQUES Printing On Non Woven Surfaces The Challenge of Improving Color Vibrancy on an Unfriendly Substrate By Antonio de Llamas Some non woven materials to be printed in flexo are composed of two basic layers: a background of plastic film covered by the actual non woven fabric. Consider the outer cover of diapers, most of which are decorated with designs, that help to sell the products in specific markets. Due to the very nature of this non woven layer, printing di- rectly on its surface is challenging but usually more cost effec- tive than printing on the background film and later laminating with a non woven coat. Printing directly on a non woven layer can be daunting because of its structure, which is made of randomly interlaced fibers that leave relatively large empty spaces in between (See Image 1). All this makes the density of the solids drop to 0.50 ANSI T, or even lower, and causes a severe reduction of gamut, as compared to a standard ISO 12647-2 (See Image 2). CHALLENGES PRINTING TO NON WOVEN • Structure consists of interlaced fibers with empty spaces in between • Density and gamut reduction compared to ISO 12647-2 • Tonal compression due to high dot gain—dots greater than 60 percent print nearly solid • Plate durometer, because non woven substrates are more abrasive than most others Image 1: Standard surface impression on non woven layer. Microphotography shows the lay down of the ink on the substrate’s fibers on Mickey’s ears, where the ink does not reach the film layer or even all the fibers of the non woven layer. Image 2: Comparative two dimensional view of color gamut at L=60 between standard ISO coated 12647 and standard impression on non woven substrate. The red space is the ISO gamut while the white represents the reduced gamut of a standard impression on a non woven material using cross linked inks that improve grip and reduce potential rubbing problems of ink, tingeing the skin of infants. 40 FLEXO FEBRUARY 2014 www.flexography.org