THE INFLUENCE OF THE FLEXO PLATE MOUNTING FOAM BACKING ON THE QUALITY OF MAGENTA COLOUR REPRODUCTION

Flexographic printing technology is relevant for producing flexible packaging. The quality of reproduction in flexographic printing is influenced by various factors such as the screen frequency, the volume of the anilox roller cells, and the hardness of the plate mounting foam backing. This study aims to investigate the impact of different plate mounting foam backings with varying hardness (Tesa Softprint Soft, Tesa Softprint Medium, and Tesa Softprint Hard) when used with the standard NX raster produced by Kodak (STD_NX). Additionally, different volumes of anilox roller cups ranging from 3,8 cm3/m2 to 11,6 cm3/m2 were considered. NX plates were produced on a Kodak Flexcel large CtP device and printed using a WGH VISTAFLEX CL8 machine with a printing speed of 300 m/min. The printing was done on a 60 μm low-density polyethylene substrate using process magenta solvent ink. The printed samples were analysed using a densitometer and a spectrophotometer (TECHKON SpectroDens) to obtain and compare the reproduction curves with the ISO printing standard 12647-6 (FOGRA 39 reference data). Furthermore, a detailed visual analysis of the printed samples was conducted using a Dino-Lite Edge digital microscope. The results of this research will provide guidance on the selection of the appropriate plate mounting foam backing in combination with the standard Kodak Flexcel NX screen and the suitable anilox cell counts in the roller. It was observed that the finest anilox (400 L/cm = 3.8 cm3/m2) yields the highest quality magenta prints and the smallest tone value increase. Additionally, the soft Tesa plate mounting foam backing offers the most accurate initial reproduction curve, staying closest to the allowed tolerance area.